Optical recording apparatus with drawing capability of visible image on disk face

ABSTRACT

A system and method of drawing a visible image on an optical disk are provided. The optical disk is rotated while a optical pickup irradiates a laser beam onto the optical disk to draw the visible image on the optical disk. The rotating state of the optical disk is detected. The optical pickup is fed in a radial direction of the optical disk. An irradiating position of the laser beam is controlled relative to the optical disk by fixing the laser beam in the radial direction of the optical disk during one rotation of the optical disk, and shifting the irradiating position of the laser beam by a first distance in the radial direction each time one rotation of the optical disk is detected. The optical pickup is fed in the radial direction by a second distance the optical disk has rotated a predetermined number of rotations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 10/282,671 filed Oct. 29, 2002 now U.S. Pat. No.7,082,094, and claims priority under 35 U.S.C. § 119 to Japan PatentApplication Nos. 2001-335608 filed on Oct. 31, 2001 and 2002-122706filed on Apr. 24, 2002. The entire disclosure of the aforementioneddocuments is herein expressly incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an optical disk recording apparatusthat can form a visual image on the face of an optical disk.

Recordable optical disks, such as a CD-R (Compact Disk-Recordable) and aCD-RW, are available on the market. To record a variety of data, such asmusic data, on these optical disks, optical disk recording apparatuses,such as CD-R drives and CD-RW drives, are employed. For recordinginformation, one of these optical disk recording apparatuses emits alaser beam, which is modulated to correspond to the information that isto be recorded and which impinges on the recording face of an opticaldisk.

For some types of optical disks, printed labels for the visualpresentation of content information, such as titles and briefdescriptions of recorded music or other recorded data, are affixed tothe other disk face opposite to the data recording side. During theprocess performed to produce these optical disks, a printer is used toprint titles or other information on a circular label sheet, forexample, and this sheet is then guided to and secured to the appropriatedisk face.

However, as is described above, the printer is required during theproduction of an optical disk whereon desired content information suchas the title of data is visually presented. Therefore, after data hasbeen recorded to the recording face of a specific disk using an opticaldisk recording apparatus, complicated handling must be performed afterthe optical disk is ejected from the optical disk recording apparatus.Namely, a separately printed label sheet prepared using a printer isaffixed to the optical disk.

SUMMARY OF THE INVENTION

To resolve this problem, it is one objective of the present invention toprovide an optical disk recording apparatus that cannot only record dataon the recording face of an optical disk, but can also draw an image toa thermo sensitive face of the disk for the visual representation ofcontent information without a new apparatus having to be separatelyprepared.

To achieve this objective, an optical disk recording apparatus accordingto the present invention is designed for recording information byirradiating a laser beam onto a recordable face of an optical disk, andcomprises: a pickup that is provided for irradiating the laser beam onthe recordable face of the optical disk; a scanning section that isprovided for scanning the laser beam relative to the recordable face ofthe optical disk; a recording control section that is provided forcontrolling the pickup and the scanning section to effect recording ofinformation on the recordable face by irradiating and scanning the laserbeam; a drawing control section that is provided for controlling thepickup and the scanning section to effect drawing of a visible image onthe recordable face of the optical disk according to image information,such that the laser beam irradiated onto the recordable face is changedbetween a first intensity incapable of acting on the recordable face ofthe optical disk and a second intensity capable of acting on therecordable face of the optical disk; and a servo section thatperiodically detects the laser beam reflected back from the recordableface of the optical disk when the laser beam has the first intensity,and that servo-controls the irradiating of the laser beam during thedrawing of the visible image based on the detection of the laser beam,wherein the drawing control section controls the pickup for forciblychanging the laser beam to the first intensity from the second intensitywhen the second intensity is maintained over a predetermined periodpursuant to the image information, thereby enabling the servo section todetect the laser beam having the first intensity for continuing theservo-control.

Preferably, the drawing control section controls the pickup for forciblychanging the laser beam to the second intensity from the first intensitywhen the first intensity is maintained over a predetermined periodpursuant to the image information, thereby enabling the servo section todetect the laser beam having the second intensity for additionallyexecuting the servo-control of the laser beam.

Preferably, the servo section controls the pickup to regulate the secondintensity of the laser beam based on the detection of the laser beamhaving the first intensity.

With this arrangement, when in accordance with image information therecordable face of the optical disk is irradiated by the laser beam, thevisual image corresponding to the image information can be formed bydiscoloring the recordable face. For this visual image forming process,when in accordance with the image information the laser beam has beenemitted for a long time at the second intensity, whereat the recordableface is visually changed, regardless of the image information, the laserbeam is adjusted and is emitted at the first intensity, whereat therecordable face is substantially unchanged. Thus, the laser beam iscontrolled based on the irradiation results.

According to another aspect of the present invention, an optical diskrecording apparatus is designed for recording information by irradiatinga laser beam onto an optical disk, and comprises: a pickup that isprovided for irradiating the laser beam on the optical disk having anoptically recordable side and a thermally sensitive side opposite to theoptically recordable side: a scanning section that is provided forscanning the laser beam relative to the optical disk; a recordingcontrol section operative when the optical disk is set to expose theoptically recordable side for controlling the pickup and the scanningsection to effect recording of information on the optically recordableside by irradiating and scanning the laser beam; a drawing controlsection operative when the optical disk is set to expose the thermallysensitive side for controlling the pickup and the scanning section toeffect drawing of a visible image on the thermally sensitive sideaccording to image information, such that the laser beam irradiated ontothe thermally sensitive side is changed between a first intensitythermally incapable of acting on the thermally sensitive side of theoptical disk and a second intensity thermally capable of acting on thethermally sensitive side of the optical disk; and a servo section thatperiodically detects the laser beam reflected back from the optical diskwhen the laser beam has the first intensity, and that servo-controls theirradiating of the laser beam during the drawing of the visible imagebased on the detection of the laser beam, wherein the drawing controlsection controls the pickup for forcibly changing the laser beam to thefirst intensity from the second intensity when the second intensity ismaintained over a predetermined period pursuant to the imageinformation, thereby enabling the servo section to detect the laser beamhaving the first intensity for continuing the servo-control.

Preferably, the drawing control section controls the pickup for forciblychanging the laser beam to the second intensity from the first intensitywhen the first intensity is maintained over a predetermined periodpursuant to the image information, thereby enabling the servo section todetect the laser beam having the second intensity for additionallyexecuting the servo-control of the laser beam.

Preferably, the servo section controls the pickup to regulate the secondintensity of the laser beam based on the detection of the laser beamhaving the first intensity.

With this arrangement, when in accordance with image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, a visual image corresponding to the image information can beformed by discoloring the thermo sensitive face. For this visual imageforming process, when in accordance with the image information the laserbeam has been emitted for a long time at the second intensity, whereatthe thermo sensitive face is changed, regardless of the imageinformation, the laser beam is adjusted and emitted at the firstintensity, whereat the thermo sensitive face is substantially unchanged.Thus, the laser beam is controlled based on the irradiation results.

According to an additional aspect of the present invention, an opticaldisk recording apparatus is designed for recording information byirradiating a laser beam onto an optical disk, and comprises: a pickupthat is provided for irradiating the laser beam to form a beam spot onthe optical disk having an optically recordable side and a thermallysensitive side opposite to the optically recordable side; a scanningsection that is provided for scanning the beam spot relative to theoptical disk; a recording control section operative when the opticaldisk is set to expose the optically recordable side for controlling thepickup and the scanning section to effect recording of information onthe optically recordable side by irradiating and scanning the laserbeam; a drawing control section operative when the optical disk is setto expose the thermally sensitive side for controlling the pickup andthe scanning section to effect drawing of a visible image on thethermally sensitive side by irradiating and scanning the laser beam; anda beam spot control section that controls a size of the beam spotgreater in the drawing of the visible image than another size of thebeam spot used in the recording of the information.

Preferably, the beam spot control section comprises a focus servo thatoperates during the recording of the information for detecting a signalof the laser beam reflected back from the optically recordable side ofthe optical disk so as to servo-control focusing of the laser beamrelative to the optically recordable side based on the detected signal,the focus servo being utilized during the drawing of the visible imagefor servo-controlling the size of the beam spot according to a signaldetected from the laser beam reflected back from the thermally sensitiveside of the optical disk.

Preferably, the beam spot control section operates during the drawing ofthe visible image for controlling the size of the beam spot according tothe laser beam reflected back from the thermally sensitive side of theoptical disk.

With this arrangement, when in accordance with image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, a visual image corresponding to the image information can beformed by discoloring the thermo sensitive face. For the visual imageforming process, the apparatus increases the diameter of the beam spotof the laser beam that is emitted for the thermo sensitive face of theoptical disk. Accordingly, during each revolution of the optical disk,the laser beam can cover a larger area, and the time required to form avisual image can be reduced.

According to a further aspect of the present invention an optical diskrecording apparatus is designed for recording information by irradiatinga laser beam onto an optical disk, and comprises: a pickup that isprovided for irradiating the laser beam on the optical disk having anoptically recordable side and a thermally sensitive side opposite to theoptically recordable side; a scanning section that is provided forscanning the laser beam over the optical disk; a recording controlsection operative when the optical disk is set to face the opticallyrecordable side to the pickup for controlling the pickup and thescanning section to effect recording of information on the opticallyrecordable side by irradiating and scanning the laser beam; a drawingcontrol section operative when the optical disk is set to face thethermally sensitive side to the pickup for controlling the pickup andthe scanning section to effect drawing of a visible image on thethermally sensitive side by irradiating and scanning the laser beam; anda gap adjusting section that adjusts a gap between the pickup and theoptical disk depending on whether the optical disk is set to face theoptically recordable side or the thermally sensitive side to the pickup,thereby respectively optimizing the recording of the information and thedrawing of the visible image.

Preferably, the gap adjusting section displaces the optical diskrelative to the pickup when the thermally sensitive side faces thepickup, from a position where the optical disk is set to face theoptically recordable side to the pickup.

Otherwise, the gap adjusting section displaces the pickup relative tothe optical disk when the thermally sensitive side faces the pickup,from a position where the pickup is set to face the optically recordableside of the optical disk

With this arrangement, when in accordance with image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, a visual image corresponding to the image information can beformed by discoloring the thermo sensitive face. After the optical diskhas been set up, whether the thermo sensitive face or the recording faceis positioned opposite the optical pickup is ascertained, and theresults are employed to adjust the positional relationship between theoptical pickup and the opposite face. Therefore, even though thedistance between the optical pickup and the opposite face varies whenthe recording face is positioned reversely to the optical pickup andwhen the thermo sensitive face is positioned opposite the opticalpickup, a variance in distance problem, which may impair various typesof controls such as focus control from being performed, can be avoided.

According to a still further aspect of the present invention, an opticaldisk recording apparatus is designed for recording information byirradiating a laser beam onto an optical disk, and comprises: a pickupthat is provided for irradiating the laser beam onto the optical diskhaving an optically recordable side formed with a guide groove in acircumferential direction of the optical disk and a thermally sensitiveside opposite to the optically recordable side; a scanning section thatis provided for scanning the laser beam over the optical disk; arecording control section operative when the optical disk is set such asto face the optically recordable side to the pickup for controlling thepickup and the scanning section to effect recording of information onthe optically recordable side by irradiating and scanning the laserbeam; a servo section operative when the optical disk is set to face thethermally sensitive side to the pickup for servo-controlling thescanning section to enable the laser beam to track the guide grooveaccording to the laser beam reflected back from the thermally sensitiveside of the optical disk; and a drawing control section operative whenthe thermally sensitive side of the optical disk faces the pickup forcontrolling the pickup to effect drawing of a visible image on thethermally sensitive side by irradiating the laser beam while the laserbeam tracks the guide groove.

Preferably, the scanning section comprises a rotary driver for rotatingthe optical disk and a radial feeder for feeding the pickup radially ofthe rotated optical disk to thereby scan the laser beam over the opticaldisk, the rotary driver being operative during the drawing of thevisible image for rotating the optical disk in a direction reversely ofthe recording of the information.

Preferably, the servo section operates during the recording of theinformation onto the optically recordable side for controlling thescanning section to enable the laser beam to track the guide groove froman inner central portion of the optical disk to an outer peripheralportion of the optical disk, and the servo section operates during thedrawing of the visible image onto the thermally sensitive side forcontrolling the scanning section to enable the laser beam to track theguide groove from the outer peripheral portion of the optical disk tothe inner central portion of the optical disk.

With this arrangement, when in accordance with the image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, the thermo sensitive face can be discolored and a visual imagecorresponding to the image information can be formed thereon. At thistime, while forming the visual image, there is no need to employ thelaser irradiation position control process, which is more complicatedthan when information is recorded to the recording face, wherein a guidegroove formed in the recording face is detected and the radiation spotposition of the laser is moved along the detected guide groove.

According to one more aspect of the present invention, an optical diskrecording apparatus is designed for recording information by irradiatinga laser beam onto an optical disk, and comprises: a pickup that isprovided for irradiating the laser beam onto the optical disk having anoptically recordable side and a thermally sensitive side opposite to theoptically recordable side; a rotary driving section that is provided forrotating the optical disk at a given rotation speed; a clock generatingsection that generates a clock signal having a frequency proportional tothe rotation speed of the optical disk; a recording control sectionoperative when the optical disk is set such as to face the opticallyrecordable side to the pickup for controlling the pickup to effectrecording of information on the optically recordable side by irradiatingthe laser beam; a drawing control section operative when the opticaldisk is set such as to face the thermally sensitive side to the pickupfor controlling the pickup to effect drawing of a visible image on thethermally sensitive side by irradiating the laser beam according togiven image information such that the laser beam is modulated eachperiod of the clock signal; a rotation detection section that detectseach time the optical disk is rotated one round during the drawing ofthe visible image; and a scanning section operative when the opticaldisk is detected to rotate one round for advancing the laser beam by onestep interval radially of the rotated optical disk to thereby scan thelaser beam over the optical disk during the drawing of the visible imageon the thermally sensitive side.

Preferably, the drawing control section operates each time the opticaldisk is detected to rotate one round for controlling the pickup toirradiate the laser beam to effect the drawing of the visible imageduring one round and controlling the pickup to suspend irradiating ofthe laser beam during next one round so as to prepare for the drawing ofthe visible image.

Preferably, the scanning section comprises a radial feeder for feedingthe pickup radially of the optical disk with a given resolution, and atracking servo for servo-controlling a position of the laser beam alonga track of the optical disk, such that the scanning section operates ifthe step interval is set smaller than the resolution of the radialfeeder for utilizing the tracking servo to advance the laser beam by thestep interval radially of the rotated optical disk.

With this arrangement, when in accordance with the image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, the thermo sensitive face can be discolored and a visual imagecorresponding to the image information can be formed thereon. For thevisual image forming process, the irradiation of the optical disk by alaser beam for forming a visual image is controlled and performed eachclock signal cycle at a frequency corresponding to the speed at whichthe optical disk is rotated, i.e., for each angular interval of theoptical disk at a predetermined angle. Therefore, a visual imagecorresponding to the image information (e.g., having a correspondingdensity) can be formed at a position correlated with each predeterminedangle of the optical disk.

According to yet another aspect of the present invention, an opticaldisk recording apparatus is designed for recording information byirradiating a laser beam onto an optical disk, and comprises: a pickupthat is provided for irradiating the laser beam onto the optical diskhaving an optically recordable side and a thermally sensitive sideopposite to the optically recordable side; a rotary driving section thatis provided for rotating the optical disk; a rotation detection sectionthat detects each time the optical disk is rotated one round from aradial reference position of the optical disk; a recording controlsection operative when the optical disk is set such as to face theoptically recordable side to the pickup for controlling the pickup toeffect recording of information on the optically recordable side byirradiating the laser beam; a drawing control section operative when theoptical disk is set such as to face the thermally sensitive side to thepickup for controlling the pickup to effect drawing of a visible imageon the thermally sensitive side by irradiating the laser beam accordingto given image information; and a scanning section operative when theoptical disk is detected to rotate one round for advancing the laserbeam by one step interval radially of the rotated optical disk tothereby scan the laser beam over the optical disk during the drawing ofthe visible image on the thermally sensitive side, wherein the drawingcontrol section operates when the optical disk is detected to rotate oneround for activating the pickup to irradiate the laser beam so as tostart the drawing of the visible image from the radial referenceposition of the optical disk, and then operates when the laser beamapproaches to the radial reference position for inactivating the pickupto stop the drawing of the visible image before the laser beam reachesthe radial reference position of the optical disk.

With this arrangement, when in accordance with the image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, the thermo sensitive face can be discolored and a visual imagecorresponding to the image information can be formed thereon. For thevisual image forming process, as the optical disk is rotated, startingat the reference position of the optical disk the laser beam is emittedto form the visual image, while the laser beam for forming a visualimage is not emitted to irradiate an area located immediately before thealready irradiated position when the laser beam returns to the referenceposition. Therefore, even when for a specific reason such as theunstable rotation of an optical disk, laser irradiation control isdisturbed and the optical disk is rotated while the laser beam isemitted at the reference position, and when the irradiation positionagain passes through the reference position, i.e., the laser irradiationposition is later moved so that it overlaps a position that has alreadybeen irradiated by the laser beam, the irradiation performed by thelaser beam to form the visual image can be prevented at the pertinentposition, and as a result, deterioration of the quality of the visualimage can be prevented.

According to yet one more aspect of the present invention, an opticaldisk recording apparatus is designed for recording information byirradiating a laser beam onto an optical disk of various types, andcomprises: a pickup that is provided for irradiating the laser beam onthe optical disk having an optically recordable side and a thermallysensitive side opposite to the optically recordable side; a scanningsection that is provided for scanning the laser beam relative to theoptical disk; a recording control section operative when the opticaldisk is set to expose the optically recordable side for controlling thepickup and the scanning section to effect recording of information onthe optically recordable side by irradiating and scanning the laserbeam; a disk detecting section that is provided for acquiringidentification information from the optical disk to identify the type ofthe optical disk set in the apparatus; and a drawing control sectionoperative when the optical disk is set to expose the thermally sensitiveside for controlling the pickup and the scanning section in accordancewith the identified type of the optical disk so as to effect drawing ofa visible image on the thermally sensitive side by irradiating andscanning the laser beam.

Preferably, the disk detecting section acquires the identificationinformation prerecorded on the thermally sensitive side of the opticaldisk.

Preferably, the disk detecting section acquires the identificationinformation prerecorded on the optically recordable side of the opticaldisk.

With this arrangement, when in accordance with the image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, the thermo sensitive face can be discolored and a visual imagecorresponding to the image information can be formed thereon. At thattime, the visual image forming process can be performed in accordancewith the type of the disk that is set up.

According to yet additional aspect of the present invention, an opticaldisk recording apparatus is designed for recording information byirradiating a laser beam onto an optical disk, and comprises: a pickupthat is provided for irradiating the laser beam on the optical diskhaving an optically recordable side and a thermally sensitive sideopposite to the optically recordable side; an encoding section that isprovided for encoding the information to be recorded; a recordingcontrol section operative when the optical disk is set to expose theoptically recordable side for controlling the pickup to irradiate thelaser beam according to the information encoded by the encoding sectionto thereby effect recording of the information in an encoded form on theoptically recordable side; a drawing control section operative when theoptical disk is set to expose the thermally sensitive side forcontrolling the pickup to irradiate the laser beam according to imageinformation so as to effect drawing of a visible image on the thermallysensitive side; and a blocking section operative during the drawing ofthe visible image for blocking the encoding section from encoding theimage information such that the visible image is drawn according to anon-encoded form of the image information.

With this arrangement, when in accordance with the image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, the thermo sensitive face can be discolored and a visual imagecorresponding to the image information can be formed thereon. For thisvisual image forming process, since the operation of the encoding meansis inhibited and the data recorded to the thermo sensitive face is notencoded, namely, the image information is not encoded. Therefore, aspecial data transmission structure is not required to form a visualimage corresponding to the image information, and the data transmissionstructure used for recording information on the recording face can beemployed to form a visual image.

According to yet a further aspect of the present invention, an opticaldisk recording apparatus is designed for recording information byirradiating a laser beam onto an optical disk, and comprises: a pickupthat is provided for irradiating the laser beam on the optical diskhaving an optically recordable side and a thermally sensitive sideopposite to the optically recordable side; a recording control sectionoperative when the optical disk is set to expose the opticallyrecordable side for controlling the pickup to irradiate the laser beamaccording to the information to thereby effect recording of theinformation; and a drawing control section operative when the opticaldisk is set to expose the thermally sensitive side for controlling thepickup to irradiate the laser beam according to image information so asto effect drawing or a visible image on the thermally sensitive side,such that the laser beam is controlled according to gradation indicatedby the image information so as to gradate the visible image drawn on thethermally sensitive side of the optical disk.

With this arrangement, when in accordance with the image information thethermo sensitive face of the optical disk is irradiated by the laserbeam, the thermo sensitive face can be discolored and a visual imagecorresponding to the image information can be formed thereon. For thevisual image forming process, the laser beam can be controlled inaccordance with the gradation level at each position (each coordinatelocation) on the thermo sensitive face indicated in the imageinformation, and a visual image can be formed where the gradation isexpressed.

According to still another aspect of the present invention, an imageforming method employs an optical disk recording apparatus having anoptical pickup which irradiates a laser beam onto a recordable face ofan optical disk to record information, and forms a visual imageaccording to image data on a thermo sensitive face of said optical diskwhich is opposite to said recordable face. The inventive methodcomprises the steps of: controlling said laser beam emitted by saidoptical pickup, so that a visual image corresponding to the image datais formed by said optical pickup on said thermo sensitive face of saidoptical disk, while an irradiation position of said laser beam emittedby said optical pickup is moved along a predetermined spiral orconcentric path on said thermo sensitive face; defining unit areas byradially dividing the thermo sensitive face such that each unit area hasa sector shape containing a predetermined number of segments of thespiral or concentric path; and controlling an irradiation timing of saidlaser beam onto the respective segments of the spiral or concentric paththat belong to each unit area, so that an optical density of each unitarea is controlled to express gradation of said visual image.

According to this method, when the laser beam is emitted in accordancewith the image information to irradiate the thermo sensitive face of theoptical disk, the thermo sensitive face is discolored and a visual imagecan be formed in accordance with the image information. For this visualimage forming process, the laser irradiation timing control can beperformed in accordance with the gradation level of each position (eachcoordinate location) on the thermo sensitive face indicated in the imageinformation, and a visual image can be obtained where the gradation isexpressed.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a schematic cross-sectional view of the structure of anoptical disk on which a visual image can be formed by an optical diskrecording apparatus according to one embodiment of the presentinvention.

FIG. 2 is a block diagram showing the configuration of the optical diskrecording apparatus according to the embodiment of the presentinvention.

FIG. 3 is a diagram showing the arrangement of an optical pickup that isone component of the optical disk recording apparatus.

FIG. 4 is a diagram for explaining the contents of image informationthat the optical disk recording apparatus employs to form a visual imageon the thermo sensitive face of the optical disk.

FIG. 5 is a diagram for explaining the laser irradiation controlprocessing performed for expressing the gradation of an image when theoptical disk recording apparatus forms a visual image on the thermosensitive face of the optical disk.

FIG. 6 is a diagram for explaining a laser beam control method employedwhen the optical disk recording apparatus forms a visual image on thethermo sensitive face of the optical disk.

FIG. 7 is a diagram for explaining the laser power control processingperformed by a laser power controller that is one component of theoptical disk recording apparatus.

FIG. 8 is a diagram showing returning light of the laser beam that isemitted for the thermo sensitive face of the optical disk by the opticalpickup of the optical disk recording apparatus.

FIG. 9 is a diagram showing an FG pulse that is generated by a frequencygenerator 21, which is one component of the optical disk recordingapparatus in accordance with the revolutions of a spindle motor, and aclock signal generated based on the FG pulse.

FIG. 10 is a flowchart for explaining the operation of the optical diskrecording apparatus.

FIG. 11 is a flowchart for explaining the operation of the optical diskrecording apparatus.

FIG. 12 is a diagram showing a disk ID recorded on the thermo sensitiveface of the optical disk.

FIG. 13 is a diagram showing shapes of the returning laser beams thatare received by the light-receiving element of the optical pickup of theoptical disk recording apparatus.

FIG. 14 is a diagram for explaining the size of the beam spot of a laserbeam that the optical pickup of the optical disk recording apparatusemits for the thermo sensitive face of the optical disk.

FIG. 15 is a diagram for explaining a method for determining that thelaser irradiation position of the optical disk recording apparatus haspassed through the reference position of the optical disk.

FIG. 16 is a diagram for explaining a method for determining that thelaser irradiation position of the optical disk recording apparatus haspassed through the reference position of the optical disk.

FIG. 17 is a timing chart for explaining the operation of the opticaldisk recording apparatus performed for emitting a laser beam to form avisual image on the thermo sensitive face of the optical disk.

FIG. 18 is a diagram showing the thermo sensitive face of the opticaldisk to which a laser beam is emitted by the optical disk recordingapparatus.

FIG. 19 is a diagram for explaining a method whereby the optical diskrecording apparatus expresses the density of a visual image that isformed on the thermo sensitive face of the optical disk.

FIG. 20 is a diagram for explaining a method whereby the optical diskrecording apparatus expresses the density of a visual image that isformed on the thermo sensitive face of the optical disk.

FIG. 21 is a diagram for explaining a method whereby the optical diskrecording apparatus expresses the density of a visual image that isformed on the thermo sensitive face of the optical disk.

FIG. 22 is a diagram for explaining a method whereby the optical diskrecording apparatus expresses the density of a visual image that isformed on the thermo sensitive face of the optical disk.

FIG. 23 is a diagram for explaining a method whereby the optical diskrecording apparatus expresses the density of a visual image that isformed on the thermo sensitive face of the optical disk.

FIG. 24 is a diagram for explaining a method for moving a laserirradiation position in the direction of the diameter of the opticaldisk when the optical disk recording apparatus forms a visual image onthe thermo sensitive face of the optical disk.

FIG. 25 is a diagram for explaining details of the laser power controlexercised by the optical disk recording apparatus.

FIG. 26 is a diagram showing the positional relationship between theoptical disk and the optical pickup for a case wherein the optical diskis set up in the optical disk recording apparatus so that the thermosensitive face is directed toward the optical pickup, and for a casewherein the optical disk is set up so that the face on the side oppositethe thermo sensitive face is directed toward the optical pickup.

FIG. 27 is a diagram showing the external appearance of an adaptor foradjusting the positional relationship between the optical disk and theoptical pickup.

FIG. 28 is a schematic diagram showing the configuration of an opticaldisk recording apparatus that has a function for adjusting thepositional relationship between the optical disk and the optical pickup.

FIG. 29 is a diagram for explaining a method for increasing the beamspot diameter of a laser beam to be emitted for the thermo sensitiveface of the optical disk.

FIG. 30 is a diagram for explaining the visual image formation methodfor moving the laser irradiation position along a pregroove that isformed in the recording face on the reverse side of the thermo sensitiveface of the optical disk.

FIG. 31 is a diagram for explaining an inhibiting area of the opticaldisk for which laser irradiation by the optical disk recording apparatusfor visual image formation is inhibited.

FIG. 32 is a block diagram showing the configuration of a modificationfor the optical disk recording apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will now be described whilereferring to the drawings.

A. Configuration of the Embodiment

The present invention relates to an optical disk recording apparatusthat emits a laser beam to irradiate the recording face of an opticaldisk. The optical disk recording apparatus has a function not only forrecording information to the recording face, but also for emitting thelaser beam to irradiate the thermo sensitive face of the optical disk onthe side opposite that of the recording face, and forming a visual imagecorresponding to the image information. First, an explanation will begiven for the configuration of an optical disk on which the visual imagecan be formed, and then the configuration of an optical disk recordingapparatus that can record information to the optical disk as well asform a visual image.

A-1. Configuration of an Optical Disk

First, FIG. 1 is a cross-sectional side view of the structure of anoptical disk, on one of the faces of which information can be recordedand on the other face of which a visible image can be formed. As isshown in FIG. 1, an optical disk D includes a protective layer 201, arecording layer (recording face) 202, a reflective layer 203, aprotective layer 204, a photosensitive layer (thermo sensitive face) 205and a protective layer 206, which are laminated in the named order. Itshould be noted that a specific structure of the optical disk D is shownin FIG. 1, and the ratios of the sizes of the individual layers is notlimited to that which is shown in FIG. 1.

A spiral pregroove (guide groove) 202 a is formed in the recording layer202, and to record information to the optical disk D, a laser beam isemitted along this pregroove 202 a. Therefore, for recordinginformation, the optical disk D is set up so that the face (hereinafterreferred to as a recording face) nearest the protective layer 201 (theupper side in FIG. 1) is directed toward the optical pickup of theoptical disk recording apparatus, and the laser beam emitted by theoptical pickup is moved along the pregroove 202 a. According to thepresent invention, to form a visual image on the face of the opticaldisk D, the optical disk D is set up so that the face (hereinafterreferred to as a thermo sensitive face) nearest the protective layer 206is directed toward the optical pickup of the optical disk recordingapparatus. Then, to form a visual image, the photosensitive layer 205 isthermally discolored by using a laser beam to irradiate desiredlocations. As is described above, the optical disk D has the samestructure as the CD-Rs that are conventionally employed, except for thephotosensitive layer 205 that is formed, and a detailed explanation ofsuch portions of the structure as the recording layer 202, will not begiven. For this specification, the “thermo sensitive face” is the facethat is discolored when irradiated by the laser beam, and the materialcomposing the photosensitive layer 205 possesses this is property.

A-2. Configuration of an Optical Disk Recording Apparatus

FIG. 2 is a block diagram showing the configuration of an optical diskrecording apparatus according to one embodiment of the presentinvention. As is shown in FIG. 2, an optical disk recording apparatus100, which is connected to a host personal computer (PC) 110, comprises:an optical pickup 10, a spindle motor 11, an RF (Radio Frequency)amplifier 12, a servo circuit 13, a decoder 15, a control unit 16, anencoder 17, a strategy circuit 18, a laser driver 19, a laser powercontroller 20, a frequency generator 21, a stepping motor 30, a motordriver 31, a motor controller 32, a PLL (Phase Locked Loop) circuit 33,an FIFO (First In First out) memory 34, a drive pulse generator 35, anda buffer memory 36.

The spindle motor 11 rotates the optical disk D to which data is to berecorded, and the servo circuit 13 controls the number of times theoptical disk D revolves. Since for recording the optical disk recordingapparatus 100 in this embodiment employs the CAV (Constant AngularVelocity) method, the spindle motor 11 rotates at a predeterminedangular velocity instructed by the control unit 16.

The optical pickup 10 is a unit that emits a laser beam for irradiatingthe optical disk D that is rotated by the spindle motor 11, and itsstructure is shown in FIG. 3. As is shown in FIG. 3. the optical pickup10 includes: a laser diode 53 for emitting a laser beam B; a diffractiongrating 58; an optical system 55 for condensing the laser beam B at theface of the optical disk D; and a light-receiving element 56 forreceiving a reflected beam.

In the optical pickup 10, the laser diode 53 receives a drive currentfrom the laser driver 19 (see FIG. 2), and emits the laser beam B at anintensity consonant with the drive current. In the optical pickup 10,the laser beam B emitted by the laser diode 53 is split into a primarybeam, a preceding beam and a succeeding beam, and these three beams passthrough a polarized beam splitter 59, a collimator lens 60, a ¼wavelength plate 61 and an object lens 62 and are condensed at the faceof the optical disk D. The three laser beams are reflected by the faceof the optical disk D and again pass through the object lens 62, the ¼wavelength plate 61 and the collimator lens 60, and are reflected by thepolarized beam splitter 59. From there, the reflected beams aretransmitted through a cylindrical lens 63 to the light-receiving element56, which receives the reflected beams and outputs them as lightreception signals to the RF amplifier 12 (see FIG. 2). Thereafter, theRF amplifier 12 transmits these signals to the control unit 16 and theservo circuit 13.

The object lens 62 is held by a focus actuator 64 and a trackingactuator 65 so that it can be moved in the light axial direction of thelaser beam B and in the direction of the diameter of the optical disk D.In accordance with a focus error signal and a tracking error signalreceived from the servo circuit 13 (see FIG. 2), the focus actuator 64and the tracking actuator 65 move the object lens 62 in the light axialdirection and in the direction of the diameter of optical disk D. Theservo circuit 13 generates the focus error signal and the tracking errorsignal based on the light reception signals transmitted by thelight-receiving element 56 through the RF amplifier 12, and moves theobject lens 62, in the manner described above, so that the focusing andtracking operations can be performed.

The optical pickup 10 includes a front monitor diode (not shown), andwhen the laser beam is emitted by the laser diode 53, the front monitordiode receives the beam and generates a current that is transmitted bythe optical pickup 10 to the laser power controller 20, in FIG. 2.

The RF amplifier 12 amplifies an RF signal that is produced by EFM(Eight to Fourteen Modulation) and is received from the optical pickup10, and outputs a resultant RF signal to the servo circuit 13 and thedecoder 15. For reproduction, the decoder 15 performs EFM demodulationfor the EFM modulated RF signal received from the RF amplifier 12 andgenerates reproduction data.

Transmitted to the servo circuit 13 is an instruction signal from thecontrol unit 16, an FG pulse signal from the frequency generator 21 thathas a frequency consonant with the number of revolutions of the spindlemotor 11, and an RF signal from the RF amplifier 12. Based on thesesignals, the servo circuit 13 rotates the spindle motor 11, and focusesor tracks the optical pickup 10. The method used for driving the spindlemotor 11 to record information to the recording face (see FIG. 1) of theoptical disk D or to form a visual image on the thermo sensitive face(see FIG. 1) of the optical disk D can be either a CAV (Constant AngularVelocity) method for driving the optical disk D to obtain apredetermined angular velocity, or a CLV (Constant Linear Velocity)method for rotating the optical disk D to obtain a predetermined linearvelocity for recording. The optical disk recording apparatus 100 in thisembodiment employs the CAV method, and the servo circuit 13 rotates thespindle motor 11 at a predetermined angular velocity designated by thecontrol unit 16.

Stored in the buffer memory 36 is information (hereinafter referred toas write data) to be recorded to the recording face of the optical diskD and information (hereinafter referred to as image information)corresponding to a visual image that is to be formed on the thermosensitive face of the optical disk D. The write data stored in thebuffer memory 36 are output to the encoder 17, while the imageinformation are output to the control unit 16.

The encoder 17 performs EFM modulation for the write data received fromthe buffer memory 36, and outputs the obtained write data to thestrategy circuit 18. The strategy circuit 18, for example, performs atime axis correction process for the EFM signal received from theencoder 17, and outputs the resultant EFM signal to the laser driver 19.

The laser driver 19, under the control of the laser power controller 20,drives the laser diode 53 (see FIG. 3) of the optical pickup 10 inaccordance with a signal that is modulated in accordance with the writedata and is received from the strategy circuit.

The laser power controller 20 controls the power for a laser beamemitted by the laser diode 53 (see FIG. 3) of the optical pickup 10.Specifically, the laser power controller 20 controls the laser driver19, so that the optical pickup 10 emits the laser beam at an intensitythat matches the optical target value of the laser power designated bythe control unit 16. The laser power control exercised by the laserpower controller 20 is feedback control, using the value of a currentsupplied by the front monitor diode of the optical pickup 10, for theemission, at the target intensity, of the laser beam by the opticalpickup 10.

The image information supplied by the host PC 110 and stored in thebuffer memory 36 are transmitted through the control unit 16 to the FIFOmemory 34 and are stored therein. In this case, the image informationstored in the FIFO memory 34, i.e., the image information supplied tothe optical disk recording apparatus 100 by the host PC 110, includesthe following information. The image information is used to form avisual image on the face of the optical disk D, and as is shown in FIG.4, information representing a gradation level (density) is written foreach of n coordinates (indicated by black dots) along multipleconcentric circles at the center O of the optical disk D. The imageinformation represents the gradation level for each of the coordinatepoints, in order from the coordinate points P11, P12, . . . and P1 n,belonging to the innermost circle to coordinate points P21, P22, . . .and P2 n, belonging to the externally adjacent circle, to the coordinatepoints along the externally adjacent circle and up to coordinate pointsPmn along the outermost circle. The data representing the gradationlevels of the coordinate points along the polar coordinate aretransmitted to the FIFO memory 34 in the above order. It should be notedthat FIG. 4 is a specific diagram clearly showing the positionalrelationships of the coordinates, and the actual coordinates are locatedat a higher density. When the host PC 110 employs a commonly used bitmap method to prepare image information to be formed on the thermosensitive face of the optical disk D, the host PC 110 need only convertbit map data into the polar coordinate data described above and transmitthe obtained image information to the optical disk recording apparatus100.

To form a visual image on the thermo sensitive face of the optical diskD based on the thus received image information, the PLL circuit 33transmits an image recording clock signal to the FIFO memory 34. Eachclock pulse of the image recording clock signal, informationrepresenting a gradation level for one of the oldest coordinate pointsthat was stored is output by the FIFO memory 34 to the drive pulsegenerator 35.

The drive pulse generator 35 generates a drive pulse to control thetiming at which a laser beam is to be emitted by the optical pickup 10.The drive pulse generator 35 generates a drive pulse having a pulsewidth that is consonant with information that is read from the FIFOmemory 34 and that represents a gradation level for each coordinatepoint. For example, when the gradation level for a specific coordinatepoint is comparatively high (the density is high), as is shown in theupper portion in FIG. 5, the drive pulse generator 35 generates a drivepulse having an extended pulse width for a write level (the secondintensity). When the gradation level is comparatively low, as is shownin the lower portion in FIG. 5, the drive pulse generator 35 generates adrive pulse having a reduced pulse width for the write level. The writelevel is a power level whereat, when the laser beam at this level isemitted and irradiates the thermo sensitive face (photosensitive layer205) of the optical disk D, the thermo sensitive face is obviouslydiscolored. And when the above described drive pulse is transmitted tothe laser driver 19, for a period corresponding to the pulse width, thelaser beam at the write level is emitted by the optical pickup 10.Therefore, when the gradation level is high, the laser beam at the writelevel is emitted longer, and a larger region in the unit area of thethermo sensitive face of the optical disk D is discolored. As a result,the user visually ascertains that the pertinent area is an area having ahigh density. In this embodiment, the length of the region in the unitarea (the unit length) to be discolored varies, so that the imageinformation is expressed at the graduation level represented therein.The servo level (the first intensity) is a power level whereat thethermo sensitive face of the optical disk D is substantially unchangedwhen irradiated by the laser at the power for this level. For a regionthat need not be discolored, only the laser beam at this servo levelonly be emitted instead of the laser beam at the write level.

In addition to generating a drive pulse that is consonant withinformation representing the gradation level for each coordinate point,regardless of this information, the drive pulse generator 35 inserts apulse at the write level having a very short cycle, or a pulse at theservo level, when the power control exercised by the laser powercontroller 20 or the focusing and the tracking control exercised by theservo circuit 13 is required. For example, when, as is shown in theupper portion in FIG. 6, a laser beam at the write level must be emittedfor a period T1 in order to express a visual image in accordance withthe gradation level at specific coordinates in the image information,and when a laser beam at the write level must be emitted for a period T1that is longer than a predetermined servo cycle ST for controlling thelaser power, a servo off-pulse (SSP1) having a very short period t isinserted at the end of the servo cycle ST. Whereas when, as is shown inthe lower portion in FIG. 6, a laser beam at the servo level must beemitted for a period equal to or longer than the servo cycle ST in orderto express a visual image in accordance with the gradation level atspecific coordinates in the image information, a servo on-pulse (SSP2)is inserted at the end of the servo cycle ST.

As is described above, the laser power controller 20 controls the laserpower based on a current (which has a value corresponding to theintensity of the emitted laser beam) supplied by the front monitor diode53 a that receives the laser beam emitted by the laser diode 53 (seeFIG. 3) of the optical pickup 10. More specifically, as is shown in FIG.7, the laser power controller 20 performs sample holding for a valuethat corresponds to the intensity of a laser beam that is emitted andthat is received by the front monitor diode 53 a (S201 and S202). Then,since the laser power controller 20 controls the laser power, when thelaser beam is emitted at the write level as a target value, i.e., when adrive pulse at the write level (see FIGS. 5 and 6) is generated, thesample holding results are employed to emit the laser beam at the targetwrite level transmitted by the control unit 16 (S203). Further since thelaser power controller 20 controls the laser power, when a laser beam isemitted at the servo level as a target value, i.e., when the drive pulseat the servo level (see FIGS. 5 and 6) is generated, the sample holdingresults are employed to emit the laser beam at the target servo leveltransmitted by the control unit 16 (S204). Therefore, when the drivepulse at the write level or the servo level is not output continuouslyfor a period longer than the predetermined servo cycle (sample cycle)ST, the servo off-pulse SSP1 or the servo on-pulse SSP2 is forciblyinserted, regardless of the contents of the image information, and thelaser power control can be exercised for each level in the abovedescribed manner.

The servo off-pulse SSP1 is inserted not only to control the laserpower, but also for the focusing or the tracking control performed bythe servo circuit 13. That is, the tracking control and the focusingcontrol are performed based on an RF signal that is received by thelight-receiving element 56 (see FIG. 3) of the optical pickup 10, i.e.,the light (reflected light) of the laser beam that is emitted by thelaser diode 53 and is returned from the optical disk D. In FIG. 8 isshown an example signal that is received by the light-receiving element56 when the photosensitive layer 205 (see FIG. 1) is irradiated by thelaser beam. As is shown in FIG. 8. the light of the laser beam at thewrite level that is reflected includes peak portion K1 at the risingtime for the laser beam and shoulder portion K2 whereat the level isthereafter maintained, and the shaded portion is regarded as energy thatwas used for discoloring the photosensitive layer 205. The energy usedfor discoloring the photosensitive layer 205 is not limited to aconstant specific value, and may vary, depending on the situation.Therefore, it is anticipated that the shape of the shaded portion willvary each time. That is, the reflected light of a laser beam at thewrite level carries much noise and stable reflected light is not alwaysobtained, and when this reflected light is employed, it will interferewith accurate focusing and tracking control. Therefore, when asdescribed above a laser beam at the write level is continuously emittedfor an extended period of time, the reflected light for a laser beam atthe servo level cannot be obtained, and the focusing control and thetracking control cannot be correctly performed.

This is why the servo off-pulse SSP1 is inserted, so that the reflectedlight for a laser beam at the servo level can be obtained periodically,and the focusing control and the tracking control are preformed based onthe reflected light that is obtained. To form a visual image on thethermo sensitive face of the optical disk D, unlike when information isto be recorded to the recording face, tracing along the pregroove (guidegroove) that is formed in advance in the optical disk D need not beperformed. Therefore, in this embodiment, the target value for thetracking control is set as a fixed value (a predetermined offset value).

This control method can be employed not only for forming imageinformation on the thermo sensitive face, but also for forming imageinformation on the recording face. That is, when a material for whichnot only the reflectivity but also the color can be changed by beingirradiated with a laser beam is employed for the recording face(recording layer 202), an image can be formed on the recording face aswell as on the thermo sensitive face. But since when a visual image isformed on the recording face, the original data recording cannot beperformed on the pertinent portion, it is preferable that the area forrecording data and the area for forming a visual image be separated.

It is also preferable that the period required for inserting the servooff-pulse SSP1 and the servo on-pulse SSP2 be minimized so as not toadversely affect various servo controls, such as the laser powercontrol, the tracking control and the focusing control when theinsertion period is greatly reduced, these various servo controls can beexercised while little affecting he visual image that is formed.

Referring again to FIG. 2, the PLL circuit (signal output means) 33multiplies the FG pulse signal at a frequency that is supplied by thefrequency generator 21 and that is consonant with the speed at which thespindle motor 11 revolves, and outputs a clock signal to be used forforming a visual image, which will be described later. The frequencygenerator 21 employs a counter-electromotive current that is obtained bythe motor driver of the spindle motor 11 and outputs the FG pulse at afrequency consonant with the number of spindle revolutions. For example,when as is shown in the upper portion in FIG. 9 the frequency generator21 generates eight FG pulses while the spindle motor 11 rotates onerevolution, i.e., when the optical disk D is rotated one revolution, asis shown in the lower portion in FIG. 9, the PLL circuit 33 outputs aclock signal having a frequency equivalent to a multiple of the FG pulse(for example, a frequency equivalent to five times the FG pulse signals,or 40 pulses at level H during one revolution of the optical disk D),i.e., outputs a clock signal having a frequency that is consonant withthe speed at which the optical disk D is rotated by the spindle motor11. As a result, the clock signal obtained by multiplying the FG pulsesignal is output by the PLL circuit 33 to the FIFO memory 34, and foreach cycle of the clock signal, i.e., for each rotation of the disk D ata specific angle, data from the FIFO memory 34 that represents thegradation level at one coordinate point is output to the drive pulsegenerator 35. The PLL circuit 33 is employed to generate a clock signalobtained by multiplying the FG pulse. And when a motor that has asatisfactorily stable driving capability is employed, instead of the PLLcircuit 33, a crystal oscillator may be employed to generate the abovedescribed clock signal obtained by multiplying the FG pulse, i.e., aclock signal having a frequency that is consonant with the speed atwhich the optical disk D is revolve.

The stepping motor 30 is a motor for moving the optical pickup 10 in thedirection of the diameter of the optical disk D that is loaded. Themotor driver 31 rotates the stepping motor 30 at a speed consonant withthe pulse signal supplied by the motor controller 32. And in accordancewith a moving start instruction that is issued by the control unit 16and that includes the direction and the distance whereat the opticalpickup 10 is moved along the diameter, the motor controller 32 generatesa corresponding pulse signal and outputs it to the motor driver 31. Whenthe stepping motor 30 moves the optical pickup 10 in the direction ofthe diameter of the optical disk D, and when the spindle motor 11rotates the optical disk D, the laser irradiation position of theoptical pickup can be set for various locations on the optical disk D,and the above described components constitute irradiation positionadjustment means.

The control unit 16 is constituted by a CPU (Central Processing Unit), aROM (Read Only Memory) and a RAM (Random Access Memory), and controlsthe individual sections of the optical disk recording apparatus 100 inaccordance with a program stored in the ROM, so that the recordingprocess for the recording face of the optical disk D and the imageforming process for the thermo sensitive face of the optical disk D areconcentrically controlled.

The configuration of the optical disk recording apparatus 100 for thisembodiment has been explained.

B. Operation for the Embodiment

The operation of the thus arranged optical disk recording apparatus 100will now be described. As is described above, the optical disk recordingapparatus 100 can record, to the recording face of the optical disk D,information such as music data received from the host PC 110, and canalso form, on the thermo sensitive face of the optical disk D, a visualimage that corresponds to the image information supplied by the host PC110. While referring to FIGS. 10 and 11, an explanation will now begiven for the operation of the optical disk recording apparatus 100 thatcan perform data recording and visual image forming.

When the optical disk D is loaded into the optical disk recordingapparatus 100, first, the control unit 16 controls the optical pickup10, for example, and determines whether the ATIP (Absolute Time InPregroove) data are recorded to the face of the optical disk D oppositethe optical pickup 10 (step Sa1). As is well known, the ATIP data arethose recorded in advance to the recording face of a CD-R along thepre-groove, and when the ATIP data have been recorded, it can beascertained that the optical disk D is set up so that the recording faceis directed toward the optical pickup 10. When the ATIP data have notbeen recorded, it can be ascertained that the optical disk D is set upso that the thermo sensitive face is directed toward the optical pickup10. That is, the control unit 16 detects the presence/absence of theATIP data, and ascertains which face of the loaded optical disk D isdirected toward the optical pickup 10. In addition to the above methodfor detecting the presence/absence of the ATIP data to determine whichface of the optical disk D is directed toward the optical pickup 10,another method may be employed. For example, when the focus servoprocess is performed, the servo contents may be employed to identify theface of the optical disk D that is directed toward the optical pickup10. That is, since the distance between the optical pickup and theopposite face of the optical disk D differs greatly, depending on whichface of the optical disk D is directed toward the optical pickup 10, thedifference in the distance affects the focus servo control value, andwith this value, the face of the loaded optical disk D that is directedtoward the optical pickup 10 can be identified.

When the ATIP data is detected on the optical disk D, it is assumed thatthe optical disk D is set up so that the recording face is directedtoward the optical pickup 10, and the control unit 16 performs a processfor recording to the recording face the write data supplied by the hostPC 110 (step Sa2). Since the process for recording the write data is thesame as that performed by a conventional optical disk recordingapparatus (a CD-R drive), no further explanation will be given.

When the ATIP data is not detected on the optical disk D, it is assumedthat the optical disk D is set up so that the thermo sensitive face isdirected toward the optical pickup 10, and the control unit 16determines whether the disk ID of the optical disk D can be obtained(step Sa3). In this embodiment, the disk ID of the optical disk D isrecorded to the thermo sensitive face of the optical disk D (see FIG. 1)having the recording face and the thermo sensitive face. For example, asis shown in FIG. 12, a visual image that corresponds to the data codefor the disk ID is recorded along the outermost circumferential edge ofthe thermo sensitive face of the optical disk D. In this embodiment, asis shown in FIG. 12, to record the disk ID to the thermo sensitive faceof the optical disk D, reflective regions 301 a and non-reflectiveregions 301 b having a length corresponding to the code are formed alongthe outermost circumferential edge. The control unit 16 traces the laserirradiation position of the optical pickup 10 along the outermost edgeof the optical disk D, and obtains the disk ID based on the reflectedlight.

Therefore, when the reflective regions 301 a and the non-reflectiveregions 301 b that correspond to the disk ID are not formed in theoutermost portion of the thermo sensitive face, it can be ascertainedthat the optical disk D is an ordinary optical disk, such as a CD-R,that does not have a thermo sensitive face. When, as in this case, adisk ID cannot be obtained, the control unit 16 ascertains that theoptical disk D is one for which visual image forming is disabled (stepSa4), and notifies a user of this determination.

When the disk ID can be obtained from the optical disk D, the controlunit 16 waits until an image forming instruction including the imageinformation is issued by the host PC 110 (step Sa5). When the imageforming instruction is issued, the control unit 16 performsinitialization in order to form a visual image on the thermo sensitiveface of the optical disk D (step Sa6). More specifically, the controlunit 16 permits the servo circuit 13 to rotate the spindle motor 11 at apredetermined angular speed, or issues to the motor controller 32 aninstruction for moving the optical pickup 10 to the initial innermostposition along the diameter of the optical disk D, and permits the motorcontroller 32 to drive the stepping motor 30.

Furthermore, in the initialization process for image forming, thecontrol unit 16 issues a target focus control value to the servo circuit13, so that the thermo sensitive face of the optical disk D isirradiated with a laser beam that has the diameter of a beam spot largerthan the one when information is recorded to the recording face.

A more specific explanation will now be given for the focusing controlprocess performed when the above described target value is designated.As is described above, the servo circuit 13 performs the focusingcontrol based on a signal output by the light-receiving element 56 ofthe optical pickup 10. In the process for recording data to therecording face of the optical disk D, the servo circuit 13 drives thefocus actuator 64 (see FIG. 3) so that circular return light A in FIG.13 is received at the center formed by four areas 56 a, 56 b, 56 c and56 d of the light-receiving element 56 in FIG. 13. That is, when theamounts of light received in the areas 56 a, 56 b, 56 c and 56 d aredefined as a, b, c and d, the focus actuator 64 is driven so that(a+c)−(b+d)=0 is established.

For forming a visual image on the thermo sensitive face of the opticaldisk D, the focusing control is performed so that the thermo sensitiveface is irradiated by the laser beam that has a diameter larger than theone when the information is recorded to the recording face. When theshape of return light received by the light-receiving element 56 in FIG.13 is an ellipse (B or C in FIG. 13), the servo circuit 13 drives thefocus actuator 64 so that this elliptical return light can be receivedby the light-receiving element 56, because the spot of the laser beam Bor C is larger than the circular laser beam A. In other words, the focusactuator 64 is driven to satisfy (a+c)−(b+d)=a (a is not 0). Therefore,in this embodiment, the control unit 16 and the servo circuit 13constitute beam spot control means.

As is described above, when the control unit 16 permits the servocircuit 13 to set a (not 0) in the initialization process for formingthe visual image, the thermo sensitive face of the optical disk D can beirradiated with the laser beam having a spot diameter larger than theone when the information is recorded to the recording face. Since thethermo sensitive face of the optical disk D is irradiated with the laserbeam of a spot diameter larger than the one when information is recordedto the recording face, the following effects can be obtained. That is,in the embodiment, while the optical disk D is rotated the laser beam isemitted for forming a visual image, as well as in recording data to therecording face. Therefore, when the diameter of the beam spot of thelaser beam is increased, a visual image can be formed across the entirethermo sensitive face of the optical disk D within a shorter period oftime. This reason will now be described while referring to FIG. 14. In acomparison between a large beam spot diameter BS and a small beam spotof the laser beam that is emitted, as specifically shown in FIG. 14,when the optical disk D is rotated one revolution, the size of the areafor forming a visual image is extended when the beam spot diameter BS islarge. Therefore, when the beam spot diameter BS is small, the opticaldisk D must be rotated more to form a visual image across the entirearea (in the example, in FIG. 14, four revolutions when the beam spotdiameter BS is large, or six revolutions when the beam spot diameter BSis small), so that an extended period of time is required for imageforming. For this reason, in the process for forming a visual image, theoptical disk recording apparatus 100 in this embodiment emits the laserbeam having a larger spot diameter than the one for data recording.

In the initialization process for image forming, the control unit 16instructs the laser power controller 20 target values for the writelevel and the servo level, so that the optical pickup 10 emits the laserbeam at the write level and the servo level that are consonant with theobtained disk ID. That is, the target values for the write level and theservo level are stored in the ROM of the control unit 16 for each of aplurality of disk ID types. The control unit 16 reads the target valuesfor the write level and the servo level that correspond to the obtaineddisk ID, and instructs these target values to the laser power controller20.

Based on the following reasons, the target power values are set inaccordance with the disk ID. The characteristic of the photosensitivefilm used as the photosensitive layer 205 may differ depending on thetype of the optical disk D, and when the characteristic differs, thecharacteristic for the level of power of the laser beam that is emittedto discolor the thermo sensitive face is accordingly changed. Therefore,while the photosensitive layer 205 of a specific optical disk D isirradiated with the laser beam at a specific write level and issatisfactorily discolored, the photosensitive layer 205 of anotheroptical disk D cannot always be discolored by being irradiated with thelaser beam at the same write level. Therefore, in this embodiment, foroptical disks that correspond to various disk IDs, the target values forthe write level and the servo level are obtained in advance throughexperiments. Then, the obtained target values are stored in the ROM incorrelation with the individual disk IDs, so that optical power controlcan be exercised in accordance with the characteristics of thephotosensitive layers 205 of various optical disks D.

When the control unit 16 performs the above described initialization,the process for forming a visual image on the thermo sensitive face ofthe optical disk D is actually started. As is shown in FIG. 11, first,the control unit 16 transmits to the FIFO memory 34 image informationreceived from the host PC 110 through the buffer memory 36 (step Sa7).Then, the control unit 16 employs an FG pulse signal received from thefrequency generator 21 to determine whether a predetermined referenceposition of the optical disk D that is rotated by the spindle motor 11has passed through the laser irradiation position of the optical pickup10 (step Sa8).

While referring to FIGS. 15 and 16, an explanation will now be given fora method for detecting the predetermined reference position, and fordetermining whether the laser irradiation position has passed throughthe reference position. As is shown in FIG. 15, the frequency generator21 outputs a predetermined number of FG pulses (eight FG pulses in thisexample) while the spindle motor 11 is rotated one revolution, i.e., theoptical disk D is rotated one revolution. Therefore, the control unit 16outputs one of the FG pulses received from the frequency generator 21 asa reference position detection pulse in synchronization with the risingtime of a reference pulse. The control unit 16 thereafter generates areference position detection pulse signal in synchronization with therising timing of the last pulse (the eighth pulse in this example) fromthe reference position detection pulse in a period equivalent to onerevolution. Since the reference position detection pulse is generated,this pulse generation timing can be identified as the timing whereat thelaser irradiation position of the optical pickup 10 passed through thereference position of the optical disk D. Specifically, as is shown inFIG. 16, assume that the laser irradiation position of the opticalpickup 10 at the timing whereat the first reference position detectionpulse is generated is defined as the position indicated by a thick line(since the optical pickup 10 can be moved in the diameter direction, anavailable irradiation position is represented by a line). Even when thereference position detection pulse is generated after one revolution thelaser irradiation position of the optical pickup 10 is the positionindicated by a thick line. As is described above, when the firstreference position detection pulse is generated, the line in thediameter direction where the laser irradiation position belongs isdefined as a reference position, and the control unit 16 can employ thereference position detection pulse signal, which is generated each timethe optical disk D is rotated once, to detect the passage of the laserirradiation position through the reference position of the optical diskD. The chained line in FIG. 16 describes an example trajectory for thelaser irradiation position from the time a specific reference positiondetection pulse was generated until the next reference positiondetection pulse was generated.

When, upon receiving the image forming instruction from the host PC 110,the control unit 16 has detected using the above method that the laserirradiation position has passed through the reference position of theoptical disk D, the control unit 16 increments, by one, a variable Rrepresenting the number of revolutions (step Sa9), and determineswhether the variable R is an odd number (step Sa10).

In this case, when upon receiving the image forming instruction thecontroller detects for the first time that the reference position hasbeen passed, R=0 (initial value)+1=1 is established, and at step Sa10 itis ascertained that the variable R is an odd number. When it isascertained that the variable R is an odd number, the control unit 16permits the optical pickup 10 to emit the laser beam to irradiate thethermo sensitive face of the optical disk D in order to form a visualimage (step Sa11). More specifically, the control unit 16 controls theindividual sections, so that image information from the FIFO memory 34are sequentially output in synchronization with a clock signal that hasbeen output by the PLL circuit 33 since the reference position detectionpulse was received. Under the control of the control unit 16, as isshown in FIG. 17, upon the reception of each clock pulse from the PLLcircuit 33, information from the FIFO memory 34 indicating the gradationlevel for one coordinate point is output to the drive pulse generator35. In accordance with the gradation level indicated by the information,the drive pulse generator 35 generates a drive pulse having acorresponding pulse width and outputs it to the laser driver 19. As aresult, the optical pickup 10 emits the laser beam at the write level toirradiate the thermo sensitive face of the optical disk D only for aperiod consonant with the gradation level of each coordinate point.Since the irradiated area is discolored, a visual image as shown in FIG.18 can be formed.

As in specifically shown in FIG. 18, since the optical disk D is rotatedby the spindle motor 11, during one clock signal cycle (a periodextending from the rising time for a pulse to the rising time for thenext pulse) the laser irradiation position of the optical pickup 10 ismoved along the circumference a distance equivalent to the regionsindicated by C in FIG. 18. While the laser irradiation position ispassing through the regions C, the period for the irradiation performedwith the laser beam at the write level is changed in accordance with thegradation level, so that in the regions C the dimensions of the areasdiscolored differ in accordance with different gradation levels. Sincethe period during which the laser beam at the write level is emittedwhile passing through each region C is adjusted in accordance with thegradation level of each coordinate point, a visual image consonant withthe image information can be formed on the thermo sensitive face of theoptical disk D.

When the control unit 16 has performed the above irradiation process forforming a visual image by using the laser beam that is controlled inaccordance with the image information, the process for the control unit16 is returned to step Sa7 and image information supplied from thebuffer memory 36 are transmitted to the FIFO memory 34. Then, thecontrol unit 16 determines whether the laser irradiation position of theoptical disk D has passed through the reference position of the opticaldisk D. When the control unit 16 determines that the laser irradiationposition has passed through the reference position, it increments thevariable R by one. And when, as a result, the variable R becomes an evennumber, the control unit 16 exercises control of the individual sectionsand halts the use of the laser beam for irradiating the optical disk Dand forming the visual image (step Sa12). More specifically, the controlunit 16 prevents information indicating the gradation level of eachcoordinate point from being transmitted, in synchronization with a clocksignal received from the PLL circuit 33, from the FIFO memory 34 to thedrive pulse generator 35. That is, after the visual image has beenformed using the laser beam at the write level, the control unit 16halts the use of the laser beam to irradiate and discolor the thermosensitive face while the optical disk D is rotated another revolution.

When the control unit 16 has halted the laser beam irradiation forvisual image formation, the control unit 16 instructs the motorcontroller 32 to move the optical pickup 10 a predetermined distancetoward the outer edge in the direction of the diameter (step Sa13). Uponreceiving this instruction, the motor controller 32 drives the steppingmotor 30 through the motor driver 31, and the optical pickup 10 is movedthe predetermined distance toward the outer edge.

As is described above, the predetermined distance whereat the opticalpickup 10 is moved in the direction of the diameter of the optical diskD can be appropriately determined in accordance with the beam spotdiameter BS (see FIG. 14) of the laser beam emitted by the opticalpickup 10. That is, to form a visual image on the thermo sensitive faceof the optical disk D, it is necessary for the laser irradiationposition of the optical pickup 10 be moved very near the surface of theoptical disk D in order to form an image having a higher quality.Therefore, when the length of the travel distance unit of the opticalpickup 10 in the direction of the diameter is defined as substantiallythe same as the beam spot diameter BS of the laser beam employed toirradiate the optical disk D, the laser beam can be emitted very nearthe surface of the optical disk D, and an image having a higher qualitycan be formed. Due to various factors, such as the property of thethermo sensitive face, a region larger than the beam spot diameter ofthe emitted laser may be colored. In this case, while taking intoaccount the width of the colored regions, the travel distance unit needonly be determined so that it does not overlap adjacent colored regions.In this embodiment, since the beam spot diameter BS is larger (e.g.,about 20 μm) than the one for recording data to the recording face, thecontrol unit 16 permits the motor controller 32 to drive the steppingmotor 30, so that the optical pickup 10 is moved in the direction of thediameter at a distance substantially equivalent to the beam spotdiameter BS. It should be noted that a recent stepping motor 30 employsthe μ step technique to adjust the travel distance using a 10 μm unit.Thus, using the stepping motor 30 to move the optical pickup 10 in unitsof 20 μm in the direction of the diameter can be satisfactorilyimplemented.

After the optical pickup 10 has been moved a predetermined distance inthe direction of the diameter, in order to change the target write levelof the laser value, the control unit 16 instructs the laser powercontroller 20 to use the updated write level whereat the laser beam issupposed to be emitted (step Sa14). In this embodiment, the method usedto form a visual image is the CAV method whereby the laser beam isemitted while the optical disk D is rotated at a consistent angularspeed. When the optical pickup 10 is moved toward the outer edge in theabove described manner, the linear velocity is increased. Therefore,when the optical pickup 10 is moved in the direction of the diameter(toward the outer edge), a target write level value is set that isgreater than the current value, so that the laser power can be obtainedat an intensity whereat, even when the linear velocity is changed, thethermo sensitive face of the optical disk D can be sufficientlydiscolored.

After the optical pickup 10 has been moved in the direction of thediameter and the target write level has been changed, the control unit16 determines whether there are any unprocessed image information forvisual image formation, i.e., whether there are still image informationthat have not been transmitted to the drive pulse generator 35. When nosuch image information are present, this processing is terminated.

When there are unprocessed image information that have not yet beentransmitted to the motor controller 32, program control returns to stepSa7, and the process for forming a visual image is repeated.Specifically, the control unit 16 transmits image information to theFIFO memory 34 (step Sa7) and determines whether the laser irradiationposition has passed through the reference position of the optical disk D(step Sa8). When the laser irradiation position has passed through thereference position, the control unit 16 increments, by one, the variableR indicating the number of revolutions (step Sa9), and determineswhether the updated variable R is an odd number (step Sa10). When thevariable R is an odd number, the control unit 16 controls the individualsections to emit the laser beam to form a visual image. And when thevariable R is an even-number, the control unit 16 halts the laseremitted to form a visual image (emits the laser beam at the servolevel), and performs the control processes, such as moving the opticalpickup 10 in the direction of the diameter and changing the target writelevel value. That is, when the laser beam (including a write level) forimage forming is emitted and used to irradiate the optical disk D duringa specific revolution, the next revolution the control unit 16 halts thelaser irradiation used for image forming, and instead, moves the opticalpickup 10 in the direction of the diameter. Since the moving of theoptical pickup 10 and the changing of the target write level areperformed during the revolution in which the image forming is notperformed, image forming is halted while the irradiation position andthe power value of the laser beam that is emitted are changed, and thelaser irradiation used for image forming can be started after theirradiation position and the intensity of the laser beam are settled.Therefore, the quality of a visual image can be protected from beingdeteriorated due to the travel of the optical pickup 10 in the directionof the diameter.

The primary operation of the optical disk recording apparatus 100 forthis embodiment has been explained. According to the optical diskrecording apparatus 100, without printing means being additionallymounted, the individual sections of the optical pickup 10 can beutilized to the extent possible for recording data to the recordingface, and the laser beam can be emitted and used for irradiating thethermo sensitive face provided for the optical disk D for the formationof a visual image in accordance with the image information.

Furthermore, in this embodiment, the laser irradiation timing iscontrolled based on a clock signal that is generated using an FG pulseproduced in accordance with the rotation of the spindle motor 11, i.e.,a clock signal that is generated in accordance with the number ofrevolutions of the optical disk D. Therefore, the optical disk recordingapparatus 100 can obtain the laser irradiation position withoutrequiring positional information from the optical disk D. And thus, theoptical disk recording apparatus 100 is not limited to only a speciallymanufactured optical disk D wherein a pregroove (a guide groove) isformed in the thermo sensitive face, and a visual image consonant withimage information can be formed on the thermo sensitive face where nopregroove is formed and no positional information is provided inadvance.

C. Modifications

The present invention is not limited to the above embodiment, and can bevariously modified as follows.

(Modification 1)

In the above embodiment, in accordance with the gradation level for eachcoordinate point that is included in image information received from thehost PC 110 in consonance with a visual image, the laser irradiationperiod is controlled so as to express the density of the visual imageformed on the thermo sensitive face of the optical disk D. However,information indicating the gradation level of each coordinate point maybe employed to change the write level of the laser power, and thedensity of a visual image may be expressed. For example, as is shown inFIG. 19 when the thermo sensitive face (photosensitive layer 205: seeFIG. 1) of the optical disk D has a characteristic according to whichthe discoloration level is moderately changed in accordance with theamount of thermal energy applied thereto, the discoloration level of thethermo sensitive face is changed to D1, D2 or D3 by the application ofdifferent amounts of energy, such as E1, E2 or E3. Therefore, as for theoptical disk D wherein the thermo sensitive face having thischaracteristic is formed, the write level of the laser light need onlybe changed in accordance with the gradation level that is indicated foreach coordinate point in the image information. Thus, portions at theindividual coordinate points on the optical disk D can be discolored inaccordance with the gradation levels, and the density of the visualimage can be expressed.

In addition to this method for changing the write level value inaccordance with the gradation level, multiple adjacent coordinate pointsmay be defined as a single unit area for expressing the gradation level,and the laser irradiation periods for these coordinates included in theunit area may be correlated with each other, so that the density of thevisual image formed on the thermo sensitive face of the optical disk Dcan be expressed. More specifically, as is shown in FIG. 20, accordingto this optical disk recording apparatus 100, the laser irradiationposition of the optical pickup 10 is moved along circular paths TR(indicated by chained lines in FIG. 20) multiple times, and the powervalue of the laser beam emitted during this travel is changed to thewrite level or the servo level in accordance with the image information.As a result a visual image can be formed.

In this modification fan-shaped regions, including a predeterminednumber (three in this example) of adjacent circular paths TR that belongto fan-shaped portions obtained by dividing the optical disk D, aredefined as unit area TA (indicated by thick lines in FIG. 20). Thetimings for emitting the laser beam to irradiate the three circularpaths TR that belong to the unit areas TA are controlled so that thedensity of the visual image can be expressed in the individual unitareas TA.

For example, to form an image having a higher density in a specific unitarea TA, the laser irradiation period is so adjusted that, as is shownin the upper portion in FIG. 21, all of the three circular paths TR thatbelong to this specific unit area TA are discolored (the discoloredportions are shown as solid portions). That is, image information isprepared so that the drive pulse generator 35 generates the drive pulsesshown in the lower portion in FIG. 21, and while the laser irradiationposition is passing along the three circular paths TR that belong to thepertinent unit area TA, the laser beam is continuously emitted at thewrite level.

For forming an image having a very low density in a specific unit areaTA (the density is not zero), the laser irradiation period is soadjusted that, as is shown in the upper portion in FIG. 22, of the threecircular paths TR that belong to the specific unit area TA, only a smallportion of the innermost circular path TR is discolored. That is, imageinformation is prepared so that the drive pulse generator 35 generatesthe drive pulses shown in the lower portion in FIG. 22 whereat the laserbeam at the write level is emitted only for one part of the periodduring which the laser irradiation position is passing along theinnermost circular path TR.

To express a specific unit area TA at an intermediate density, the laserirradiation period is adjusted so that, as is shown in the upper portionin FIG. 23, of three circular paths TR that belong to the unit area TA,the entire portion along the innermost circular path TR and the halfportion along the middle circular path TR are discolored. Specifically,image information is prepared so that the drive pulse generator 35generates the drive pulses shown in the lower portion in FIG. 23 whereatthe laser beam at the write level is emitted for a period during whichthe laser irradiation position is passing along the innermost circuitpath TR, and for one part of the period during which the laserirradiation position is passing along the intermediate circular path TR.

The host PC 110 generates, in advance, image information for which theabove gradation expression is provided for each unit area TA, andtransmits the image information to the optical disk recording apparatus100. Therefore, a visual image for which the gradation expression isprovided for each unit area TA can be formed on the thermo sensitiveface of the optical disk D.

(Modification 2)

In the above described embodiment, when a visual image has been formedby emitting the laser beam while the optical disk D is rotated once fromthe reference position, the feeding control process is performed, i.e.,the optical pickup 10 is moved a predetermined distance in the outerdirection of the diameter, and the laser irradiation position is movedvery near the surface of the optical disk D. However, some mechanismsfor driving the optical pickup 10 in the direction of the diametercannot control the travel distance represented by units of 20 μm. For anoptical disk recording apparatus wherein such a driving mechanism ismounted, the size of a portion on the optical disk that the laser beamcannot radiate is increased, and as a result, the quality of a visualimage formed on the thermo sensitive face is deteriorated.

When the adjustability of the drive means for moving the optical pickup10 in the direction of the diameter is low, the control by the drivemeans for moving the optical pickup 10 in the direction of the diameterand the tracking control of the optical pickup 10 may be employed toadjust the laser irradiation position along the diameter using a smallerunit, such one of 20 μm. More specifically, as is shown in FIG. 24,first, the diameter-direction drive means, such as a stepping motor,moves the optical pickup 10 to position A. Then, while the opticalpickup 10 is fixed at position A, tracking control is performed so as toset the laser irradiation position along the diameter to position A1.Then, with the irradiation position set at A1, the laser beam is emittedwhile the optical disk D is rotated, so that a visual image is formed.And when the visual image formation with the irradiation position fixedat A1 is terminated, the laser irradiation position is moved outwarddistance a by the tracking control and is set at position A2, while theoptical pickup 10 is fixed to the position A. Thereafter, while theoptical disk D is rotated under this condition, the laser beam isemitted to form a visual image. Similarly, while the optical pickup D isfixed to the position A, the laser irradiation position is moved in theorder A3, A4 and A5 by the tracking control, and image formation iscontinued.

When the image formation is completed while the laser irradiationposition is set to position A5, the drive means moves the optical pickup10 outward a distance A, and sets the optical pickup 10 at position B.When the optical pickup 10 is fixed at the position B, the laserirradiation position is moved outward by the tracking control thedistance a to positions B1, B2, B3, B4 and B5, and the image formingprocess is performed. Since the control exercised by the stepping motorfor moving the optical pickup 10 in the direction of the diameter andthe tracking control are employed, the laser irradiation position can bemoved smaller distance units, even when the adjustability of the drivemeans for moving the optical pickup 10 in the direction of the diameteris low.

(Modification 3)

The optical disk recording apparatus 100 for the above embodimentemploys the CAV method whereby, for forming a visual image, a laser beamis emitted while the optical disk D is rotated at a consistent angularvelocity. However, the CLV method whereby the linear velocity isconsistent may be employed. When the CAV method is employed, in order toobtain a visual image having a high quality, the write level value forthe laser beam should be increased as the laser irradiation position ismoved outward across the optical disk D; however, when the CLV method isemployed, the write level value need not be changed. Therefore, thequality of an image formed on the thermo sensitive face of the opticaldisk will not be deteriorated due to the fluctuation of the target laserpower value.

(Modification 4)

Further, in the above embodiment, the laser power controller 20 controlsthe laser power based on the light-receiving results obtained at thefront monitor diode 53 a of the optical pickup 10, so that the laserbeam is emitted at the target write level or the target servo level (seeFIG. 7). In addition, in the above embodiment, the light-receivingresults obtained by the front monitor diode 53 a when the laser diode 53emits the laser at the target write level are employed, so that theintensity of the laser beam emitted by the laser diode 53 can match thetarget write level. Furthermore, the light-receiving results obtained bythe front monitor diode 53 a when the laser beam is emitted by the laserdiode 53 at the target servo level are employed, so that the intensityof the laser beam emitted by the laser diode 53 can match the targetservo level value.

In the process for controlling the laser power by using the target writelevel and the target servo level, in addition to the results obtained byreceiving the laser beam emitted at these target levels, the resultsobtained by receiving the laser beam emitted at the target servo levelmay also be employed to control the laser power at the target writelevel, as well as at the target servo level. More specifically, based onthe results (the current value) obtained by receiving the laser beamemitted at the target servo level, the laser power controller 20 obtainsa current value SI that is to be supplied to the laser diode 53 in orderto permit the laser diode 53 to emit the laser beam at the target servolevel value SM, as is shown in the upper portion in FIG. 25 When thecurrent value SI is obtained that is to be supplied for the emission ofthe laser beam at the target servo level SM, as is shown in the lowerportion in FIG. 25 a relationship (a linear function) between a suppliedcurrent value, which was acquired in advance through an experiment, andthe output laser power is obtained for the laser diode 53 by employingthe current value SI and an inclination a that is used to represent thisrelationship by using the linear function. Then, the laser power circuit20 employs the obtained relationship and the target write level WM setby the control unit 16 to obtain a value WI for a current that is to besupplied to the laser diode 53 in order to emit the laser beam at thewrite level. The laser power controller 20 permits the laser driver 19to supply the thus obtained current WI to the laser diode 53. In thismanner, the emission of the laser beam at the write level can becontrolled without using the results obtained by receiving the laserbeam that is emitted at the target write level.

In the above embodiment and this modification, while the laser beam isbeing emitted for forming a visual image, the light-receiving results atthe front monitor diode 53 a are employed to perform feedback controlfor the laser power. However, the feedback control may not be performedduring visual image formation and the laser power may be controlled, sothat a laser irradiation test is conducted before the visual imageformation, and the obtained light-receiving results for the frontmonitor diode 53 a are employed to supply a current value to the laserdiode 53. When a period required for image forming is short, the travelof the optical pickup 10 and the fluctuation of the ambient environment(the temperature) is small, so that the laser power may besatisfactorily controlled even without feedback control being performed.Therefore, an optical disk recording apparatus that can perform imageforming within a short period of time can also employ the laser powercontrol that does not accompany the feedback control.

(Modification 5)

In the above embodiment, the disk ID is read from the outermost edge ofthe thermo sensitive face of the optical disk D to identify the disktype loaded in the optical disk recording apparatus 100, and the laserpower control is exercised in accordance with the disk type identified(see FIG. 12). A disk ID may be read from the read-in area of therecording face of the optical disk D, and during the process for forminga visual image on the thermo sensitive face of the optical disk D, thelaser power control may be exercised in accordance with the disk typethat is identified by the disk ID. In order to obtain the disk ID fromthe read-in area of the recording face, first, the user loads theoptical disk D to direct the recording face toward the optical pickup10, and the optical disk recording apparatus 100 reads the disk ID fromthe read-in area for the optical disk D, and instructs the user toreverse and re-insert the disk. When the optical disk D is set so thatthe thermo sensitive face is directed toward the optical pickup 10, theoptical disk recording apparatus 100 can perform the laser power controlin accordance with the disk ID obtained from the read-in area, and forma visual image on the thermo sensitive face of the optical disk D.

(Modification 6)

As was described in the above embodiment, the optical disk recordingapparatus 100 uses the individual sections of the optical pickup 10 thatrecords information to the recording face, so that a visual image can beformed on the thermo sensitive face, which is the reverse side relativeto the recording face. As for a CD-R, the protective layer 201 overlaidon the recording layer 202 in FIG. 1 has a thickness of 1.2 mm, whilethe thickness of the protective layer 206 on the other face is verysmall. Therefore, as is shown in FIG. 26, distances d1 and d2 (relativepositional relationships) between the position of the layer of theoptical disk D, which a laser beam should irradiate, and the positionsof the optical pickup 10 differ by about 1.2 mm, depending on whichface, either the recording face or the thermo sensitive face, isdirected toward the optical pickup 10 when the optical disk D is set up.

When the optical pickup 10 is designed on the assumption that thedistance d1 between the optical pickup 10 and the recording face of theoptical disk D is a focusing distance, its focus actuator 64 (see FIG.3) may not satisfactorily perform focusing control when the distancebetween the optical pickup 10 and the face to be irradiated reaches d2.Therefore, a mechanism may be provided whereby, when the optical disk Dis set with the thermo sensitive face directed toward the optical pickup10, the optical disk D is held at a position separated from the opticalpickup 10 by a distance of about 1.2 mm, so that the distance betweenthe thermo sensitive face and the optical pickup 10 substantiallymatches d1.

As this mechanism, as is shown in FIG. 27, an adaptor (relative positionadjustment means) 271 may be employed that is detachable from a chuckingportion 270 in the center of the optical disk D. When the optical disk Dis to be loaded in the optical disk recording apparatus 100 so that thethermo sensitive face thereof is directed toward the optical pickup 10,the adaptor 271 need only be mounted for the optical disk D.

Furthermore, the optical disk recording apparatus 100 may include amechanism that can be moved between a position near where the opticaldisk D is loaded into the optical recording apparatus 100 and a positionat a distance therefrom, and that changes the position whereat theoptical disk D is held. Only when the optical disk D is set up so thatthe thermo sensitive face is directed toward the optical pickup 10 maythe mechanism be moved to the position near where the optical disk D isset up and used to adjust the position whereat the optical disk D isheld.

In addition to the use of the adaptor 271 to move the position of theoptical disk D away from the optical pickup 10, as is shown in FIG. 28,a drive mechanism (relative position adjustment means) 280 may beprovided whereby, when the optical disk D is set up with the thermosensitive face directed toward the optical pickup 10, the optical pickup10 is moved away from the optical disk D until the distance between thethermo sensitive face and the optical pickup is d1.

(Modification 7)

In the above embodiment, the focusing control has been performed inaccordance with light that is returned from the optical disk D and isreceived by the light-receiving element 56 (see FIG. 3) of the opticalpickup 10, and for this focusing control, a laser beam having a spotdiameter larger than that for recording data on the recording face hasbeen emitted is used to irradiate the thermo sensitive face of theoptical disk D. Further, in the embodiment, in order to increase thespot diameter, the focus actuator 64 was driven so that thelight-receiving results obtained by the light-receiving element 56 werethe elliptical shapes B and C shown in FIG. 13. Instead of the lightvalues received in the four areas 56 a, 56 b, 56 c and 56 d of thelight-receiving element 56, the total amount of light received in allthe areas of the light-receiving element 56 may be employed to performfocusing control, so that the thermo sensitive face of the optical diskD can be irradiated with a laser beam having a spot diameter larger thanthe one when the elliptical shapes B and C are obtained as thelight-receiving results. That is, when the spot diameter of the laserbeam to be emitted for the thermo sensitive face of the optical disk Dis increased, the light-receiving element 56 cannot receive all thereturning light, and as is indicated by circle Z in FIG. 29, returninglight for an area larger than the light-receiving area of thelight-receiving element 56 is obtained. In other words, the total amountof light received by the light-receiving element 56 is reduced.Therefore, when the servo circuit 13 drives the focus actuator 64, sothat the total amount of light received by the light-receiving element56 is smaller than the total amount of light received when thelight-receiving results, such as the circle A and elliptics B and C inFIG. 13, are obtained, a laser beam having a larger spot diameter can beemitted for the thermo sensitive face of the optical disk D.

(Modification 8)

When the protective layer 205 (see FIG. 1) of the optical disk D isformed of a very transparent material, even when the optical disk D isset up with the thermo sensitive face directed toward the optical pickup10, the optical disk recording apparatus 100 can detect, from light(reflective light) returned from the optical disk D, a pregroove (guidegroove) formed in the recording face of the optical disk D. Morespecifically, unlike the case wherein the laser beam is emitted for therecording face, the returning write level is high when the pregroove isirradiated with the laser beam, while the returning write level is lowwhen the land portion is irradiated. Therefore, the pregroove can bedetected by examining the level of the returning light, and as a result,the tracking control can be performed along the pregroove.

When the optical disk D is set up with the thermo sensitive facedirected toward the optical pickup 10, and when the tracking control isenabled along the pregroove formed in the recording face on the reverseside, the laser beam may be emitted to form a visual image, while thelaser irradiation position is moved along the pregroove. When thepregroove formed in the recording face on the reverse side relative tothe thermo sensitive face is detected to perform the tracking control inorder to move the laser irradiation position along the pregroove, thespindle motor 11 is rotated in the direction opposite to that when datais recorded to the recording face, and the optical disk D is rotated inthe reverse direction. The reason the optical disk is rotated in thereverse direction will now be described while referring to FIG. 30. Asis shown in the upper portion in FIG. 30, when a spiral pre-groove PB isformed in the recording face of the optical disk D, viewed from therecording face it is a clockwise spiral. But when, as is shown in thelower portion in FIG. 30, the pregroove PB is viewed from the thermosensitive face, which is the opposite face, it is a counterclockwisespiral. Therefore, when the optical disk D is rotated from the innermostposition PBS along the pregroove PB in the same direction as it isrotated for data recording, the laser irradiation position cannot bemoved along the pregroove. Therefore, when the laser irradiationposition is to be moved along the pregroove PB in order to form a visualimage by emitting the laser beam for the thermo sensitive face of theoptical disk D, the optical disk D is rotated in the direction oppositeto the direction in which the data is recorded to the recording face.

Therefore, when the laser irradiation position is moved along thepregroove PB and the laser irradiation timing and the laser power arecontrolled in accordance with image information in order to form avisual image in the same manner as in the embodiment, the control unit16 need only instruct the servo circuit 13 to rotate the spindle motor11 in the direction opposite to the direction in which the data isrecorded to the recording face.

Further, when a visual image is to be formed on the thermo sensitiveface while the laser irradiation position is moved along the pregroovePB formed in the recording face, assuming that the laser irradiationstart position is defined as the outermost position PBE of the pregroovePB, the laser irradiation position can be moved along the pregroove PBeven when the optical disk D is rotated in the same direction as that inwhich it is rotated for recording.

(Modification 9)

In the above embodiment, the control unit 16 may inhibit the irradiationperformed by an image forming laser beam (a laser beam at a write level)in a predetermined inhibiting area KA of the thermo sensitive face ofthe optical disk D in FIG. 31. When the laser irradiation position ismoved clockwise from the above described reference position (see FIG.16), as is shown in FIG. 31, the inhibiting area KA is a fan-shaped areahaving a predetermined angle θ in the counterclockwise direction fromthe reference position. That is, when the optical disk D is rotated andwhen the laser irradiation position is moved from the reference positionand the laser beam is emitted to form a visual image, the inhibitingarea KA is the area the laser irradiation position passes throughimmediately before the laser irradiation position is returned to thereference position.

To inhibit the formation of a visual image in the inhibiting area KA,the control unit 16 need only perform data conversion, i.e., change to“0” the gradation level of the coordinates for the inhibiting area KA inthe image information supplied from the host PC 110. Through this dataconversion, even when the drive pulse generator 35 accurately generatesa drive pulse in accordance with the data obtained by data conversion,the laser beam at the write level is not emitted when the laserirradiation position passes through the inhibiting area KA, and as aresult, a visual image cannot be formed in the inhibiting area KA.

When the laser irradiation for forming a visual image is halted for theinhibiting area KA, the following effects are obtained. When the imageforming is performed in synchronization with the clock signal receivedfrom the PLL circuit 33, the rotational velocity of the spindle motorfor one revolution is varied slightly, and accordingly, the cycle of theclock signal output by the PLL circuit 33 is fluctuated. Due to thefluctuation of the clock signal, which is a synchronization signal forimage forming, it may be that, as is shown in FIG. 31, the trajectory(indicated by a chained line in FIG. 3) of the laser irradiationposition will draw substantially one revolution after the laserirradiation to form a visual image was started at the reference positionKK, and that the laser beam will be emitted at a position KT where thelaser beam has passed through the reference position, while the laserbeam is supposed to be emitted to express an image at a position KCimmediately following the reference position. That is, when emitted thelaser beam is overlapped, so that the laser beam that is originallysupposed to be emitted to express the image at the position KC,immediately before the reference position, is also emitted at theposition KT in an area in which the laser beam has already been emittedto form a visual image. As a result, a failure in the thus obtainedvisual image will occur. Therefore, even when the click signal generatedby the PLL circuit 33 is fluctuated, the image information is convertedin order to set the inhibiting area KA, so that a failure caused by theuse of the laser beam to form in the same position a second visual imagecan be prevented.

(Modification 10)

An optical disk recording apparatus 100′ having the configuration shownin FIG. 32 may be employed instead of the optical disk recordingapparatus 100 for the above embodiment. As is shown in FIG. 32, theoptical disk recording apparatus 100 differs from the optical diskrecording apparatus 100 in the above embodiment in that the FIFO memory34 and the drive pulse generator 35 are not included and an encoder 320is provided instead of the encoder 17.

The encoder 320, as well as the encoder 17 in the embodiment, is acircuit for performing EFM modulation and CIRC (Cross InterleaveReed-Solomon Code) conversion of received data. The encoder 320temporarily accumulates the received data in a memory, performs theabove modulation for the accumulated data, and outputs the resultantdata to a strategy circuit 18′. In addition, based on a modulationON/OFF signal received from a control unit 16, the encoder 320determines whether the data received from a buffer memory should beoutput through a process such as the EFM modulation, or should be outputwithout the EFM modulation being performed. When a modulation ON signalis received from the control unit 16, the encoder 36 performs the EFMmodulation for the data received from the buffer memory 36, and outputsthe resultant data to the strategy circuit 18′. When the modulation OFFsignal is transmitted by the control unit 16, in synchronization with aclock signal received from a PLL circuit 33, the encoder 320 outputs thedata received from the buffer memory 36, without performing anymodulation.

Upon receiving an instruction that is entered by a user through a userinterface (not shown), the control unit 16 outputs a modulation ON/OFFsignal to the encoder 320. More specifically, the control unit 16outputs a modulation OFF signal when an instruction is received from theuser to form a visual image on the thermo sensitive face, or outputs amodulation ON signal when an instruction is received to record data tothe recording face. Instead of outputting a modulation ON/OFF signal inaccordance with the user's instruction, the control unit 16 may output amodulation ON/OFF signal in accordance with the face of the optical diskthat is directed toward the optical pickup 10. In this case, amodulation OFP signal must be output when the optical disk D is set upwith the thermo sensitive face directed toward the optical pickup 10,and a modulation ON signal must be output when the optical disk D is setup with the recording face directed toward the optical pickup 10.

With this configuration, when an instruction is issued by the user torecord data to the recording face, the control unit 16 outputs themodulation ON signal to the encoder 320. The write data to be recordedto the recording face of the optical disk D is transmitted from a hostPC 110 to the buffer memory 36, and is then transmitted from the buffermemory 36 to the encoder 320. Upon receiving the modulation ON signal,the encoder 320 performs the EFM modulation for the write data receivedfrom the buffer memory 36, and outputs the resultant data to thestrategy circuit 18′. The strategy circuit 18′ performs time axialcorrection of the EFM modulated data, generates a drive pulse to drive alaser driver 19, and outputs the drive pulse to the laser driver 19. Inaccordance with the drive pulse, the laser driver 19 supplies a drivecurrent to the laser diode 53 (see FIG. 3) of the optical pickup 10, andthe optical pickup 10 emits the laser beam for the recording face of theoptical disk D in order to record the data supplied from the host PC110.

When an instruction is issued by the user to form a visual image on thethermo sensitive face, the control unit 16 outputs the modulation OFFsignal to the encoder 320. Image information that corresponds to avisual image to be formed on the thermo sensitive face of the opticaldisk D is transmitted from the host PC 110 to the buffer memory 36, andis then transmitted from the buffer memory 36 to the internal memory ofthe encoder 320. Upon receiving the modulation OFF signal, the encoder320 does not perform any modulation for the image information receivedfrom the buffer memory 36, and sequentially outputs data (informationindicating a gradation level) for the individual coordinates to thestrategy circuit 18′ in synchronization with the clock signal suppliedby the PLL circuit 33. The strategy circuit 18′, as well as the drivepulse generator 35 in the above embodiment, generates a drive pulsebased on data indicating a gradation level for each coordinate pointthat is sequentially supplied, and outputs the drive pulse to the laserdriver 19. In accordance with the drive pulse, the laser driver 19supplies the drive current to the laser diode 53 (see FIG. 3) of theoptical pickup 10, and the optical pickup 10 emits the laser beam toform on the thermo sensitive face of the optical disk D a visual imagethat is consonant with the image information transmitted by the host PC110.

As is described above, since the encoder 320 can perform or haltmodulation depending on visual image formation or data recording, theFIFO memory 34 and the drive pulse generator 35 used only for visualimage formation can be removed, and with a simple structure, the opticaldisk recording apparatus 100′ can obtain a visual image formationfunction and a data recording function.

(Modification 11)

A visual image may also be formed on the recording face (recording layer202) of the optical disk D. Since it is well known that when a laserbeam is emitted for the recording layer 202 that is equal to or greaterthan a predetermined intensity, the reflectivity at the irradiatedportion is changed, a visual image can be formed by emitting the laserbeam across a large range that can be identified visually. Or, when therecording layer 202 is formed of a material the state of which ischanged, e.g., the laser irradiation area is hollowed out or raised, avisual image can also be formed by using the property of this material.

To form a visual image on the recording face (recording layer 202), thedata for forming a visual image need only be recorded along the guidegroove (pregroove) formed in the recording layer 202. Further, as wellas when a visual image is formed on the thermo sensitive face(photosensitive layer 205), the beam spot diameter of the laser beam tobe emitted for the recording layer 202 may be increased, and the datamay be recorded without using the guide groove. That is, the interval(track pitch) of the guide grooves is a very small value of only severalμm, and even when data recording is not performed along the guidegroove, the resolution of a visual image to be formed will not bereduced. Strictly speaking, the surface of the recording layer 205 isrough because the guide grooves are formed therein; however, since thedepth of the grooves is a small value of merely several μm, when forminga visual image the recording layer 202 can be regarded as being flat.

So long as the technique related to this invention is employed, a visualimage can be formed not only on the thermo sensitive face(photosensitive layer 205) but also on the recording face (recordinglayer 202), without requiring any special apparatus.

(Modification 12)

When a visual image is formed on the recording layer 202 of the opticaldisk D, data can naturally not be recorded to the region bearing thevisual image. Therefore, in the write area (recording layer 202) of theoptical disk D, a region for forming a visual image may be determined inadvance. For example, when original data recording is performed in anarea extending from the innermost position of the disk to apredetermined position (address) and a visual image is formed on theouter area, the original area for recording data will not be lost.

Further, an area wherein no data is recorded (a non-recorded area) maybe detected after the original data recording is completed, and a visualimage may be formed in the detected non-recorded area.

(Modification 13)

Data (image information) to be recorded for forming a visual image maybe stored in advance in the memory (not shown) of the optical diskrecording apparatus 100. For example, data with which numerals 0 to 9are to be recorded as visual images on the optical disk D are preparedin the memory. When the user designates a numeral to be formed on theoptical disk D, the corresponding write data may be read from the memoryand recorded to the optical disk D to form a visual image.

Furthermore, the regular data recording is performed outwardly acrossthe disk, and when the data recording is completed, time stampinformation indicating the recording date and time may be automaticallygenerated as a visual image without a user's instruction being required.The time stamp information may be supplied from an external apparatus(host PC 110) to the optical disk recording apparatus 100.

Further, when the original data recording is completed, signatureinformation indicating a user name and the contents of the write datamay be generated as a visual image. Through manipulation by the user,the signature information need only be supplied by the host PC 110 tothe optical disk recording apparatus 100. Or, the user may directlyoperate the optical disk recording apparatus 100 to enter (register) thesignature information.

As is described above, according to the present invention, not only candata be recorded to the recording face of an optical disk, but alsovisible data can be recorded to the thermo sensitive face, without a newapparatus being separately prepared.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

1. An optical disk apparatus capable of drawing a visible image on anoptical disk by irradiating a laser beam onto the optical disk, theapparatus comprising: a rotating section arranged to rotate the opticaldisk; a detecting section arranged to detect a rotating state of theoptical disk; an optical pickup arranged to irradiate the laser beamonto the optical disk which is rotated by the rotating section, so thatthe visible image is drawn on the optical disk; a feeding sectionarranged to feed the optical pickup in a radial direction of the opticaldisk; and a tracking control section arranged to control an irradiatingposition of the laser beam relative to the optical disk, wherein thetracking control section fixes the irradiating position of the laserbeam at a first position in the radial direction of the optical diskduring a rotation of the optical disk, and shifts the irradiatingposition of the laser beam by a first distance in the radial directionbased on the detected rotating state to a second position at which theirradiating position of the laser beam is fixed during another rotationof the optical disk, and wherein the feeding section feeds the opticalpickup in the radial direction by a second distance when the detectingsection detects that the optical disk has rotated a predetermined numberof rotations, wherein the predetermined number of rotations is greaterthan one rotation.
 2. The optical disk apparatus according to claim 1,wherein the tracking control section shifts the irradiating position ofthe laser beam by the first distance in the radial direction toward anouter periphery of the optical disk.
 3. The optical disk apparatusaccording to claim 1, wherein the feeding section feeds the opticalpickup by the second distance in the radial direction toward an outerperiphery of the optical disk.
 4. The optical disk apparatus accordingto claim 1, wherein the tracking control section shifts the irradiatingposition of the laser beam by the first distance each time the detectingsection detects one rotation of the optical disk, such that the firstdistance is set constant for every rotation of the optical disk.
 5. Theoptical disk apparatus according to claim 4, wherein the trackingcontrol section shifts the irradiating position of the laser beam by thefirst distance which is set substantially identical to a spot diameterof the laser beam irradiated from the optical pickup.
 6. The opticaldisk apparatus according to claim 1, wherein the feeding section feedsthe optical pickup by the second distance when the detecting sectiondetects that the optical disk has rotated a predetermined number ofrotations, such that the second distance is set constant every time thedetecting section detects that the optical disk has rotated thepredetermined number of rotations.
 7. The optical disk apparatusaccording to claim 1, wherein the rotating section rotates the opticaldisk at a constant angular velocity.
 8. The optical disk apparatusaccording to claim 7, wherein the rotating section has a spindle motorarranged to rotate the optical disk, and the rotating section controlsthe rotation of the optical disk based on pulses having a frequencycorresponding to a rotation number of the spindle motor.
 9. The opticaldisk apparatus according to claim 8, wherein the detecting sectioncounts a number of rotations of the optical disk based on the pulseshaving the frequency corresponding to the rotation number of the spindlemotor.
 10. The optical disk apparatus according to claim 1, wherein therotation section rotates the optical disk at a constant linear velocity.11. The optical disk apparatus according to claim 1, wherein thedetecting section counts a number of rotations of the optical disk withreference to a predetermined radius of the optical disk.
 12. The opticaldisk apparatus according to claim 1, wherein the optical pickupirradiates the laser beam onto the optical disk having a thermallysensitive layer, so that the visible image is drawn in the thermallysensitive layer of the optical disk.
 13. The optical disk apparatusaccording to claim 1, wherein the optical pickup irradiates the laserbeam onto the optical disk having a data recordable layer, so that thevisible image is drawn in the data recordable layer of the optical disk.14. The optical disk apparatus to claim 13, wherein the optical pickupirradiates the laser beam onto a free part of the data record layerwhere data is not recorded, so that the visible image is drawn in thefree part of the data recordable layer, separately from other part ofthe data recordable layer where data is already recorded.
 15. Theoptical disk apparatus according to claim 1, wherein the trackingcontrol system fixes the irradiating position of the laser beam in theradial direction in response to an input of a constant offset voltage.16. The optical disk apparatus according to claim 1, wherein the opticaldisk includes a pregroove, a data recordable layer and a thermallysensitive layer, and wherein the optical pickup irradiates the laserbeam with a guide of the pregroove while recording data in the datarecordable layer, and irradiates the laser beam independent of a guideof the pregroove while drawing the visible image in the thermallysensitive layer.
 17. The optical disk apparatus according to claim 16,wherein the optical pickup irradiates the laser beam having a first spotdiameter into the data recordable layer when the data is recorded in thedata recordable layer, and irradiates the laser beam having a secondspot diameter, which is set greater than the first spot diameter, intothe thermally sensitive layer when the visible image is drawn in thethermally sensitive layer.
 18. The optical disk apparatus according toclaim 16, wherein the optical pickup irradiates the laser beam having afirst spot diameter into the data recordable layer when the data isrecorded in the data recordable layer, and irradiates the laser beamhaving a second spot diameter, which is set identical to the first spotdiameter, into the thermally sensitive layer when the visible image isdrawn in the thermally sensitive layer.
 19. A method of drawing avisible image on an optical disk with an optical pickup for irradiatinga laser beam onto the optical disk, the method comprising the acts of:rotating the optical disk while the optical pickup irradiates the laserbeam onto the optical disk to draw the visible image on the opticaldisk; detecting a rotating state of the optical disk; feeding theoptical pickup in a radial direction of the optical disk; andcontrolling an irradiating position of the laser beam relative to theoptical disk, wherein the act of controlling includes fixing theirradiating position of the laser beam at a first position in the radialdirection of the optical disk during a rotation of the optical disk, andshifting the irradiating position of the laser beam by a first distancein the radial direction based on the detected rotating state to a secondposition at which the irradiating position of the laser beam is fixedduring another rotation of the optical disk, and wherein the act offeeding includes feeding the optical pickup in the radial direction by asecond distance when it is detected that the optical disk has rotated apredetermined number of rotations, wherein the predetermined number ofrotations is greater than one rotation.
 20. The method according toclaim 19, wherein the act of controlling includes shifting theirradiating position of the laser beam by the first distance in theradial direction toward an outer periphery of the optical disk.
 21. Themethod according to claim 19, wherein the act of feeding includesfeeding the optical pickup by the second distance in the radialdirection toward an outer periphery of the optical disk.
 22. The methodaccording to claim 19, wherein the act of controlling includes shiftingthe irradiating position of the laser beam by the first distance eachtime the one rotation of the optical disk is detected, such that thefirst distance is set constant for every rotation of the optical disk.23. The method according to claim 22, wherein the act of controllingincludes shifting the irradiating position of the laser beam by thefirst distance which is set substantially identical to a spot diameterof the laser beam irradiated from the optical pickup.
 24. The methodaccording to claim 19, wherein the act of feeding includes feeding theoptical pickup by the second distance when the detecting step detectsthat the optical disk has rotated a predetermined number of rotations,such that the second distance is set constant every time it is detectedthat the optical disk has rotated the predetermined number of rotations.25. The method according to claim 19, wherein the optical disk isrotated at a constant angular velocity.
 26. The method according toclaim 25, wherein the act of rotating involves a spindle motor rotatingthe optical disk, and controlling the rotation of the optical disk basedon pulses having a frequency corresponding to a rotation number of thespindle motor.
 27. The method according to claim 26, wherein the act ofdetecting includes counting a number of rotations of the optical diskbased on the pulses having the frequency corresponding to the rotationnumber of the spindle motor.
 28. The method according to claim 19,wherein the optical disk is rotated at a constant linear velocity. 29.The method according to claim 19, wherein the act of detecting includescounting a number of rotations of the optical disk with reference to apredetermined raduis of the optical disk.
 30. The method according toclaim 19, wherein the optical pickup irradiates the laser beam onto theoptical disk having a thermally sensitive layer, so that the visibleimage is drawn in the thermally sensitive layer of the optical disk. 31.The method according to claim 19, wherein the optical pickup irradiatesthe laser beam onto the optical disk having a data recordable layer, sothat the visible image is drawn in the data recordable layer of theoptical disk.
 32. The method according to claim 31, wherein the opticalpickup irradiates the laser beam onto a free part of the data recordablelayer where data is not recorded, so that the visible image is drawn inthe free part of the data recordable layer, separately from other partof the data recordable layer where data is already recorded.
 33. Themethod according to claim 19, wherein the act of controlling includesfixing the irradiating position of the laser beam in the radialdirection in response to an input of a constant offset voltage.
 34. Themethod according to claim 19, wherein the optical disk includes apregroove, a data recordable layer and a thermally sensitive layer, andwherein the optical pickup irradiates the laser beam with a guide of thepregroove when recording data in the data recordable layer, andirradiates the laser beam independent of a guide of the pregroove whendrawing the visible image in the thermally sensitive layer.
 35. Themethod according to claim 34, wherein the optical pickup irradiates thelaser beam having a first spot diameter into the data recordable layerwhen the data is recorded in the data recordable layer, and irradiatesthe laser beam having a second spot diameter, which is set greater thanthe first spot diameter, into the thermally sensitive layer when thevisible image is drawn in the thermally sensitive layer.
 36. The methodaccording to claim 34, wherein the optical pickup irradiates the laserbeam having a first spot diameter into the data recordable layer whenthe data is recorded in the data recordable layer, and irradiates thelaser beam having a second spot diameter, which is set identical to thefirst spot diameter, into the thermally sensitive layer when the visibleimage is drawn in the thermally sensitive layer.
 37. A systemcomprising: an optical disk having a thermally sensitive layer and adata recordable layer; a rotating section arranged to rotate the opticaldisk; a detecting section arranged to detect a rotating state of theoptical disk; an optical pickup arranged to irradiate a laser beam ontothe optical disk which is rotated by the rotating section, so that avisible image is drawn on the optical disk; a feeding section arrangedto feed the optical pickup in a radial direction of the optical disk;and a tracking control section arranged to control an irradiatingposition of the laser beam relative to the optical disk, wherein thetracking control section fixes the irradiating position of the laserbeam at a first position in the radial direction of the optical diskduring a rotation of the optical disk, and shifts the irradiatingposition of the laser beam by a first distance in the radial directionbased on the detected rotating state to a second position at which theirradiating position of the laser beam is fixed during another rotationof the optical disk, and wherein the feeding section feeds the opticalpickup in the radial direction by a second distance when the detectingsection detects that the optical disk has rotated a predetermined numberof rotations, wherein the predetermined number of rotations is greaterthan one rotation.
 38. The system according to claim 37, wherein thetracking control section shifts the irradiating position of the laserbeam by the first distance in the radial direction toward an outerperiphery of the optical disk.
 39. The system according to claim 37,wherein the feeding section feeds the optical pickup by the seconddistance in the radial direction toward an outer periphery of theoptical disk.
 40. The system according to claim 37, wherein the trackingcontrol section shifts the irradiating position of the laser beam by thefirst distance each time the detecting section detects one rotation ofthe optical disk, such that the first distance is set constant for everyrotation of the optical disk.
 41. The system according to claim 40,wherein the tracking control section shifts the irradiating position ofthe laser beam by the first distance which is set substantiallyidentical to a spot diameter of the laser beam irradiated from theoptical pickup.
 42. The system according to claim 37, wherein thefeeding section feeds the optical pickup by the second distance when thedetecting section detects that the optical disk has rotated apredetermined number of rotations, such that the second distance is setconstant every time the detecting section detects that the optical diskhas rotated the predetermined number of rotations.
 43. The systemaccording to claim 37, wherein the rotating section rotates the opticaldisk at a constant angular velocity.
 44. The system according to claim43, wherein the rotating section has a spindle motor arranged to rotatethe optical disk, and the rotating section controls the rotation of theoptical disk based on pulses having a frequency corresponding to arotation number of the spindle motor.
 45. The system according to claim44, wherein the detecting section counts a number of rotations of theoptical disk based on the pulses having the frequency corresponding tothe rotation number of the spindle motor.
 46. The system according toclaim 37, wherein the rotation section rotates the optical disk at aconstant linear velocity.
 47. The system according to claim 37, whereinthe detecting section counts a number of rotations of the optical diskwith reference to a predetermined radius of the optical disk.
 48. Thesystem according to claim 37, wherein the optical pickup irradiates thelaser beam onto the thermally sensitive layer, so that the visible imageis drawn in the thermally sensitive layer of the optical disk.
 49. Thesystem according to claim 37, wherein the optical pickup irradiates thelaser beam onto the data recordable layer, so that the visible image isdrawn in the data recordable layer of the optical disk.
 50. The systemto claim 49, wherein the optical pickup irradiates the laser beam onto afree part of the data record layer where data is not recorded, so thatthe visible image is drawn in the free part of the data recordablelayer, separately from other part of the data recordable layer wheredata is already recorded.
 51. The system according to claim 37, whereinthe tracking control system fixes the irradiating position of the laserbeam in the radial direction in response to an input of a constantoffset voltage.
 52. The system according to claim 37, wherein theoptical disk includes a pregroove, a data recordable layer and athermally sensitive layer, and wherein the optical pickup irradiates thelaser beam with a guide of the pregroove while recording data in thedata recordable layer, and irradiates the laser beam independent of aguide of the pregroove while drawing the visible image in the thermallysensitive layer.
 53. The system according to claim 52, wherein theoptical pickup irradiates the laser beam having a first spot diameterinto the data recordable layer when the data is recorded in the datarecordable layer, and irradiates the laser beam having a second spotdiameter, which is set greater than the first spot diameter, into thethermally sensitive layer when the visible image is drawn in thethermally sensitive layer.
 54. The system according to claim 53, whereinthe optical pickup layer when the data is recorded in the datarecordable layer, and irradiates the laser beam having a second spotdiameter, which is set identical to the first spot diameter, into thethermally sensitive layer when the visible image is drawn in thethermally sensitive layer.